Physics Calculators

Boltzmann Factor Calculator

Calculate the Boltzmann factor and population ratio for two energy levels at a given temperature. Enter energy in eV or joules and temperature in Kelvin.

Gravitational Field Strength Calculator

Calculate g = GM/r² at any distance from a mass. Includes escape velocity and a chart showing how field strength drops with distance. Supports m, km, and AU.

Inductance Calculator — Solenoid and Toroid

Calculate inductance for solenoid and toroid coils using core permeability, turns, and geometry. Includes inductive reactance at a given frequency and energy stored.

Kirchhoff Laws Calculator

Solve series and parallel resistor circuits using Kirchhoff's Voltage and Current Laws. Finds total resistance, total current, and voltage or current across each resistor.

Nuclear Radius Calculator

Calculate the radius of any atomic nucleus using r = r₀ × A^(1/3), where A is the mass number. Also computes nuclear volume, density, and surface area for any element.

Phase Angle Calculator — RL, RC, and RLC Circuits

Calculate impedance and phase angle for RL, RC, and RLC circuits at any frequency. Returns total impedance Z, phase angle φ, and power factor cos(φ) in degrees and radians.

Relative Velocity Calculator

Calculate relative velocity between two objects using classical subtraction or the relativistic Einstein addition formula for speeds near the speed of light.

Resonance Frequency Calculator

Calculate resonance frequency for vibrating strings and acoustic pipes. Covers string harmonics using tension and linear density, and pipe modes for open and closed pipes.

Shear Stress Calculator — Direct and Torsional

Calculate direct shear stress (F/A) or torsional shear stress in circular shafts (Tr/J). Returns results in Pa, kPa, MPa, and psi for mechanical engineering applications.

Sound Intensity and Decibel Calculator

Calculate sound intensity from source power and distance, then convert to decibels. Based on the inverse-square law. Chart shows how dB drops with distance from the source.

Stress and Strain Calculator

Calculate normal stress, strain, and deformation for structural members. Covers σ=F/A, strain ε=σ/E, elongation δ=FL/(AE), and factor of safety.

Surface Tension Calculator

Calculate capillary rise height from surface tension, contact angle, density, and tube radius. Or solve for surface tension from a measured rise height.

Adiabatic Compression Calculator

Calculate temperature and pressure after adiabatic compression or expansion. Covers diesel engine ignition, turbocharger heating, and bicycle pump compression.

Atwood Machine Calculator

Calculate acceleration, tension, and velocity in an Atwood machine from two hanging masses. A classic physics lab tool for measuring gravitational acceleration.

Bohr Model Calculator

Calculate hydrogen energy levels, orbital radius, and photon wavelengths with the Bohr model. Enter quantum number n, and optionally a transition target level.

Conservation of Energy Calculator

Calculate the total mechanical energy, maximum height, and velocity at different points using conservation of energy. Enter mass, height, and velocity.

Conservation of Momentum Calculator

Calculate final velocities after any 1D collision using momentum conservation and a coefficient of restitution from 0 (inelastic) to 1 (elastic).

Cyclotron Radius & Larmor Radius Calculator

Calculate the Larmor (cyclotron) radius and cyclotron frequency of a charged particle in a magnetic field. Used in particle accelerators and mass spectrometers.

Elastic Collision Calculator

Calculate post-collision velocities in a 1D elastic collision. Enter both masses and initial velocities to find final speeds and verify energy conservation.

Electron Drift Velocity Calculator

Calculate electron drift velocity in a conductor from current, wire diameter, and material. Reveals how slowly electrons actually move through household wiring.

Gyroscope Precession Calculator

Calculate gyroscope precession rate from spin speed, mass, radius, and pivot distance. Shows why a spinning top does not fall and how gyroscopes navigate aircraft.

Hubble's Law Distance Calculator

Calculate galactic recession velocity and distance using Hubble's law. Enter distance in megaparsecs or redshift to explore the expansion of the universe.

Impact Force Calculator

Calculate impact force from mass, velocity, and stopping time or distance. Find peak force during collisions, falls, and sudden stops in newtons and pounds.

Impulse Calculator

Calculate impulse from force and time, or from mass and velocity change. Enter any two variables to find the third using the impulse-momentum theorem.

Inelastic Collision Calculator

Calculate the final velocity and kinetic energy lost in a perfectly inelastic collision where two objects stick together after impact.

Mach Number Calculator

Calculate Mach number from speed and temperature. Find the speed of sound at any temperature and identify the flight regime from subsonic to hypersonic.

Net Force Calculator

Calculate the resultant net force from multiple forces at different angles. Enter up to three forces with magnitude and direction to get the vector sum.

Newton's Second Law Calculator

Calculate force, mass, or acceleration using Newton's Second Law. Enter any two values to solve for the third and see results in both SI and imperial units.

Normal Force Calculator

Calculate the normal force on a flat or inclined surface. Enter mass and surface angle to find the perpendicular contact force in newtons.

Optical Power Calculator (Diopters)

Calculate the focal length and optical power of a lens in diopters. Enter object and image distances to find magnification and lens strength.

Orbital Period Calculator (Kepler's Third Law)

Calculate orbital period from orbital radius and central body mass. Find revolution time for satellites, moons, and planets using Kepler's third law.

Rolling Motion Down Incline Calculator

Calculate how fast a sphere, cylinder, or ring rolls down an inclined plane. Compare rolling versus sliding and see how moment of inertia shapes the result.

Rotational Motion Calculator

Convert between angular velocity, linear velocity, and radius. Calculate torque from force and lever arm length. Covers key rotational mechanics formulas.

Schwarzschild Radius Calculator

Calculate the Schwarzschild radius and event horizon size for any mass. Find how small Earth or the Sun must be compressed to become a black hole.

Series Circuit Calculator

Calculate total resistance, current, and individual voltage drops for resistors connected in series. Enter supply voltage and up to four resistance values.

Spring Potential Energy Calculator

Calculate potential energy stored in a compressed or stretched spring. Enter the spring constant and displacement to find stored elastic energy in joules.

Stellar Parallax Distance Calculator

Calculate stellar distance from parallax angle in arcseconds or milliarcseconds. Convert between parsecs, light-years, and AU for nearby star measurements.

Stokes Law Settling Velocity Calculator

Calculate Stokes drag force and settling velocity for a spherical particle in a viscous fluid. Used for sedimentation, aerosol settling, and filtration analysis.

Tidal Force Calculator

Calculate the tidal force across an extended body due to gravity gradient. Find tidal forces from the Moon on Earth, or any mass at any distance.

Van der Waals Real Gas Calculator

Calculate real gas pressure using the van der Waals equation and compare it to ideal gas behavior. Enter moles, temperature, volume, and gas type.

Weight from Mass Calculator

Calculate the gravitational weight of any mass on Earth or other planets. Compare weight across the solar system from Mercury to Neptune.

Work-Energy Theorem Calculator

Calculate net work done on an object from its change in kinetic energy. Enter mass and initial and final velocities to apply the work-energy theorem.

Young's Modulus & Stress-Strain Calculator

Calculate stress, strain, and Young's modulus from applied force, cross-section area, original length, and deformation. Find elastic modulus for any material.

Beat Frequency Calculator

Calculate the beat frequency between two close tones. Used for instrument tuning, ultrasonic detection, and acoustics. Find beat period and pitch midpoint.

Brewster Angle Calculator

Calculate Brewster angle from two refractive indices. At this incidence reflected light is fully polarized — used in optics, photography, and laser design.

Coriolis Force Calculator

Calculate Coriolis force on a moving object from mass, velocity, and latitude. Predicts apparent deflection on a rotating Earth for ballistics.

Mirror Equation Calculator

Calculate image distance, magnification, and image properties for curved mirrors using 1/f = 1/d_o + 1/d_i. Works for concave and convex mirrors.

RC Discharge Time Calculator

Calculate the discharge time of a capacitor through a resistor for any target voltage. Includes the time constant tau, half-life, and 5-tau rule.

Reduced Mass Calculator

Calculate the reduced mass of a two-body system from individual masses. Used in orbital mechanics, molecular vibration, and quantum mechanics problems.

Inclined Plane Force Calculator

Calculate the force needed to push a load up a ramp. Includes friction coefficient, mechanical advantage, and comparison to lifting the load straight up.

Otto Cycle Efficiency Calculator

Calculate the ideal thermal efficiency of a gasoline engine from compression ratio using the Otto cycle formula. See how design choices affect fuel efficiency.

Bouncing Ball Calculator

Calculate bounce height after each impact. Enter drop height, ball type, and gravity. Shows all bounce heights, total distance, and an exponential decay chart.

Compton Scattering Calculator

Calculate Compton wavelength shift, scattered photon energy, and recoil electron kinetic energy using the Compton effect formula for X-ray scattering.

Electron Volt (eV) Converter

Convert between electron volts (eV), keV, MeV, GeV, TeV, joules, kcal, and temperature. Includes wavelength and frequency equivalents for photons.

Fluid Viscosity Calculator

Calculate dynamic and kinematic viscosity and Reynolds number for common fluids. Convert between cP, mPa·s, cSt, and SSU with temperature data for water.

ISA Standard Atmosphere Calculator

Calculate standard atmospheric pressure, temperature, density, and speed of sound at any altitude using the International Standard Atmosphere (ISA) model.

Length Contraction Calculator (Special Relativity)

Calculate relativistic length contraction at any speed. Find contracted length, Lorentz factor, and velocity in multiple units with thought experiments.

Lorentz Factor (γ) Calculator

Calculate the Lorentz factor from velocity. Find time dilation, length contraction, and relativistic mass at any fraction of the speed of light.

Maxwell-Boltzmann Speed Distribution Calculator

Calculate the Maxwell-Boltzmann speed distribution for gas molecules. Find the most probable speed, mean speed, and RMS speed for any gas and temperature.

Nuclear Reaction Q-Value Calculator

Calculate the Q-value of nuclear reactions from mass defect. Supports alpha decay, beta decay, proton capture, and custom reactions with energy in MeV.

Quantum Harmonic Oscillator Energy Levels

Calculate quantized energy levels of a quantum harmonic oscillator. Find eigenvalues, zero-point energy, transition frequencies, and ladder operator results.

Radioactive Decay Chain Calculator

Simulate sequential radioactive decay chains. Calculate activity and remaining quantity of parent and daughter nuclides over time using Bateman equations.

Radioactivity Unit Converter (Becquerel ↔ Curie)

Convert between radioactivity units: Becquerel (Bq), Curie (Ci), Rutherford (Rd), and disintegrations per minute (dpm). Includes activity-to-mass calculations.

Relativistic Kinetic Energy Calculator

Calculate relativistic kinetic energy, total energy, and rest energy at any velocity. Compare classical vs relativistic predictions and the speed of light.

Sound Level Addition Calculator

Add multiple decibel levels using logarithmic combination. Calculate combined SPL from two or more noise sources and convert between dB and sound intensity.

Statistical Mechanics Partition Function Calculator

Calculate partition function Z for quantum oscillators and two-level systems. Returns average energy, heat capacity, entropy, and free energy.

Time Dilation Calculator (Special Relativity)

Calculate relativistic time dilation, Lorentz factor, and length contraction at any speed. Enter velocity as fraction of c, m/s, or km/s with real examples.

Tsiolkovsky Rocket Equation Calculator

Calculate delta-v, propellant mass, exhaust velocity, and specific impulse using the Tsiolkovsky rocket equation. Covers single-stage and multi-stage rockets.

Wave Interference Calculator

Calculate wave interference path difference, constructive and destructive conditions, and double-slit fringe positions for Young's experiment and thin film.

Boltzmann Entropy Calculator

Calculate entropy using Boltzmann's formula S = k*ln(W). Explore the connection between microstates, thermodynamic probability, and statistical mechanics.

Earthquake Magnitude & Energy Calculator

Convert between Richter scale and Moment Magnitude (Mw), calculate energy released, and compare earthquake sizes. Used by seismologists worldwide.

Heisenberg Uncertainty Principle Calculator

Calculate the minimum uncertainty in position or momentum using Heisenberg's Uncertainty Principle. Fundamental to quantum mechanics.

Photoelectric Effect Calculator

Calculate the kinetic energy of ejected electrons from the photoelectric effect. Enter photon wavelength or frequency and material work function.

Centrifuge RPM to RCF Converter

Convert centrifuge speed between RPM and RCF using RCF = 1.118 × r × (RPM/1000)². Enter rotor radius in mm for bidirectional conversion used in biology labs.

AC Power Factor Calculator

Calculate power factor, reactive power, and apparent power for AC circuits. Determines if power factor correction is needed.

Angular Acceleration Calculator

Calculate angular acceleration from torque and moment of inertia, or from change in angular velocity over time. Shows resulting angle rotated.

Angular Velocity to Linear Speed Calculator

Convert between angular velocity and linear (tangential) speed at a given radius. Also calculates centripetal acceleration.

Bernoulli's Equation Flow Calculator

Solve Bernoulli's equation for pressure, velocity, or height at two points in a fluid flow. Supports water, air, and custom fluid density.

Blackbody Peak Wavelength Calculator (Wien's Law)

Calculate the peak emission wavelength of a blackbody radiator from its temperature. Identify the color of thermal radiation and total radiated power.

Capacitor Energy Storage Calculator

Calculate energy stored in a capacitor using E = 0.5*C*V^2. Returns energy in joules, millijoules, and charge in coulombs for any capacitance and voltage.

Carnot Efficiency Calculator

Calculate the maximum theoretical efficiency of a heat engine (Carnot efficiency) and the maximum COP for heat pumps and refrigerators.

Critical Angle for Total Internal Reflection

Calculate the critical angle for total internal reflection when light travels from a denser to a less dense medium. Used in fiber optics and prism design.

De Broglie Wavelength Calculator

Calculate the de Broglie wavelength of a particle from its mass and velocity. Shows why electrons behave as waves while everyday objects do not.

Diffraction Grating Calculator

Calculate the diffraction angle for different orders of light through a diffraction grating. Find wavelength separation and angular dispersion.

Electric Flux Calculator

Calculate electric flux through a surface using Φ = E·A·cos(θ). Also applies Gauss's law to find the enclosed charge from flux.

Electric Potential Calculator

Calculate electric potential at any distance from a point charge using V=kQ/r. Solve for voltage, charge, or distance with Coulomb's constant k=8.9875e9.

Fermi Energy Calculator

Calculate the Fermi energy of a metal from its electron number density. Shows Fermi energy in eV and Fermi temperature. Includes presets for common metals.

Fluid Pressure at Depth Calculator

Calculate hydrostatic pressure at any depth in a fluid. Supports seawater, fresh water, mercury, and custom densities. Shows pressure in Pa, atm, bar, and PSI.

Gravitational Acceleration at Altitude

Calculate how gravitational acceleration g changes with altitude above Earth's surface. Shows weight reduction and compares to notable altitudes.

Gravitational Potential Energy Calculator

Calculate gravitational potential energy near Earth's surface (mgh) or in the general case (-GMm/r). Includes body presets and escape velocity.

Heat of Vaporization/Fusion Calculator

Calculate the heat required to vaporize or melt a substance using Q = mL. Includes common substances with known latent heat values.

Heat Pump COP Calculator

Calculate the coefficient of performance (COP) of a heat pump or refrigeration system. Compare to Carnot COP and estimate energy savings.

Hydraulic Lift Force Calculator (Pascal's Law)

Calculate the output force of a hydraulic lift using Pascal's law. Find the mechanical advantage from input and output piston areas with worked examples.

Induced EMF Calculator (Faraday's Law)

Calculate the induced EMF from changing magnetic flux (Faraday's law) or from motional EMF (B·L·v). Essential for generator and transformer design.

Inductor Energy Storage Calculator

Calculate energy stored in an inductor using E = ½LI² from inductance in henries and current in amperes. Returns energy in joules and millijoules.

LC Circuit Resonant Frequency Calculator

Calculate the resonant frequency of an LC circuit from inductance and capacitance. Shows frequency in Hz, kHz, and angular frequency in rad/s.

Lorentz Force Calculator

Calculate magnetic and electric force on a moving charged particle using F = q(E + v×B). Enter charge, velocity, and field strengths to get Newtons.

Magnetic Flux Calculator

Calculate magnetic flux using the formula Phi = B times A times cos(theta). Enter field strength, surface area, and angle to find total flux in webers.

Malus's Law — Polarized Light Calculator

Calculate transmitted polarized light intensity through a filter using Malus's Law: I = I0*cos^2(theta). Solve for angle, initial, or output intensity.

Moment of Inertia Calculator

Calculate the moment of inertia for common shapes: solid disk, hollow cylinder, solid sphere, hollow sphere, thin rod, and rectangular plate.

Optical Fiber Numerical Aperture Calculator

Calculate the numerical aperture and acceptance angle of an optical fiber from core and cladding refractive indices. Also calculates the V-number.

Parallel Resistors Calculator

Calculate the equivalent resistance of up to 4 resistors connected in parallel. Also calculates current through each resistor if voltage is known.

Photon Energy Calculator

Calculate the energy of a photon from its wavelength or frequency. Shows energy in joules and electron volts, and identifies the spectral region.

RC Circuit Charge Time Calculator

Calculate the voltage across a capacitor at any time during charging. Shows the time constants (63%, 87%, 95%, 99%) for RC circuit charging.

Relativistic Momentum Calculator

Calculate the relativistic momentum, kinetic energy, and total energy of a particle moving at a significant fraction of the speed of light.

Rotational Kinetic Energy Calculator

Calculate the kinetic energy of a rotating object from its moment of inertia and angular velocity. Compare to translational kinetic energy.

Simple Harmonic Motion Calculator

Calculate the period, frequency, max velocity, max acceleration, and total energy of a spring-mass system undergoing simple harmonic motion.

Simple Machine Mechanical Advantage Calculator

Calculate the mechanical advantage of levers, inclined planes, screws, pulleys, and wheel-and-axle systems. Select a machine type to get started.

Single-Slit Diffraction Calculator

Calculate the positions of diffraction minima from a single slit. Find angles and positions on a screen for the first 3 dark fringes.

Solenoid Magnetic Field Calculator

Calculate the magnetic field inside a solenoid from turn count, length, and current using B=μ₀nI. Includes worked examples for air-core and iron-core solenoids.

Standing Wave Resonant Frequency Calculator

Calculate the resonant frequencies of standing waves on strings, open pipes, and closed pipes. Shows the first 5 harmonics.

Thin Film Interference Calculator

Calculate which visible wavelengths are reinforced or cancelled by thin film interference. Explains soap bubble colors, oil slick iridescence, and AR coatings.

Transformer Turns Ratio Calculator

Calculate the turns ratio of an ideal transformer. Find secondary voltage, secondary turns, or current ratio from the transformer equations.

Shadow Length Calculator

Calculate the length of a shadow cast by any object based on its height and the sun's elevation angle. Works in meters or feet.

Entropy Change Calculator (Thermodynamics)

Calculate entropy change for chemical and physical processes. Find entropy from heat transfer, temperature, and reactions using the thermodynamic relationship.

Nuclear Binding Energy Calculator

Calculate the nuclear binding energy and mass defect of an atomic nucleus from proton and neutron counts using Einstein mass-energy equivalence.

Acceleration from Force Calculator

Calculate acceleration, force, or mass using Newton's Second Law (F=ma). Enter any two values to solve for the third, with SI and imperial unit options.

Angular Momentum Calculator

Calculate angular momentum of a rotating object using mass, velocity, and radius, or moment of inertia and angular velocity.

Brachistochrone Trajectory Calculator

Calculate interplanetary travel time using the flip-and-burn maneuver: accelerate to the midpoint, flip, and decelerate. Enter destination and thrust level.

Buoyancy Force Calculator

Calculate the buoyancy (upward) force on any object submerged in a fluid. Uses Archimedes Principle. Supports water, seawater, oil, and custom fluids.

Centrifugal Force Calculator

Calculate centrifugal (centripetal) force for rotating objects. Enter mass, velocity, and radius to find the outward force in Newtons and other units.

Coulomb's Force Calculator

Calculate the electrostatic force between two charged particles using Coulomb's Law. Enter charge and distance to find the force.

Decibel Distance Calculator

Calculate SPL at any distance using the inverse square law (6 dB per distance doubling). Enter source dB and reference distance for speaker placement planning.

Doppler Effect Frequency Calculator

Calculate the observed frequency shift due to the Doppler effect. Works for sound, light, and radar applications with source or observer motion.

Drag Coefficient Calculator

Calculate aerodynamic drag force from velocity, frontal area, and drag coefficient (Cd). Returns drag force in Newtons and pounds-force for air or fluid.

Electric Field Strength Calculator

Calculate electric field strength from a point charge (E = kQ/r²) or parallel plates (E = V/d). Covers field direction, superposition, and field line density.

Electrical Conductivity Calculator

Calculate electrical conductivity, resistivity, resistance, or conductance from material properties and wire dimensions using standard electrical formulas.

Heat Capacity Calculator

Calculate heat energy needed to raise or lower a substance's temperature using Q=mcΔT. Enter mass, specific heat capacity, and temperature change in C or F.

Kinetic Energy Calculator

Calculate kinetic energy of any moving object from mass and velocity. Returns energy in Joules, kilojoules, calories, and BTU in metric and imperial units.

Lens Power (Diopter) Calculator

Calculate lens power in diopters from focal length, or find focal length from a diopter value. Covers eyeglasses, contact lenses, and optical instruments.

Light Intensity (Inverse Square Law) Calculator

Calculate how light intensity changes with distance using the inverse square law. Useful for photography, lighting design, and physics.

Magnetic Force Calculator

Calculate magnetic force on a moving charge (F = qvB) or a wire (F = BIL) from charge, velocity, field, and angle. Used for motors and physics problems.

Projectile Range Calculator

Calculate the range, maximum height, and time of flight of a projectile using launch speed and angle. Supports metric and imperial units.

Radioactive Half-Life Remaining Calculator

Calculate remaining radioactive material after any elapsed time. Enter initial amount and half-life to get remaining quantity and decay percentage.

Refraction Index Calculator

Calculate the angle of refraction using Snell's Law. Find the refractive index or refracted angle when light passes between two materials.

Relativistic Rocket Calculator

Calculate time dilation for a relativistic rocket at constant acceleration. Enter distance in light-years and g-force to compare ship time versus Earth time.

Specific Heat Calculator

Calculate heat energy absorbed or released, temperature change, or specific heat capacity using Q = mcΔT. Supports metric and imperial units.

Static Electricity Voltage Calculator

Estimate the voltage of a static electric discharge based on material type, humidity, and activity. Understand why static shocks happen and how to prevent them.

Stefan-Boltzmann Radiation Calculator

Calculate thermal radiation power emitted by an object using the Stefan-Boltzmann law. Find heat radiated by temperature and surface area.

Thermal Conductivity Heat Flow Calculator

Calculate heat flow rate through a material using thermal conductivity, thickness, area, and temperature difference. Useful for insulation and building design.

Wave Speed Calculator

Calculate wave speed, frequency, or wavelength using v = f × λ — solve for any one variable. Covers sound in air, light, water waves, and seismic applications.

Friction Force Calculator

Calculate static and kinetic friction force. Enter mass, angle, and friction coefficient to find friction, normal force, and net force.

Snell's Law Calculator

Calculate light refraction angles using Snell's Law. Enter refractive indices and incident angle to find refraction angle and critical angle.

Spring Force Calculator (Hooke's Law)

Calculate spring force, displacement, or spring constant using Hooke's Law. Includes potential energy and oscillation frequency.

Thin Lens Equation Calculator

Calculate focal length, object distance, or image distance using the thin lens equation. Supports converging and diverging lenses.

Battery Bank Calculator

Size a battery bank for off-grid solar systems. Calculate battery capacity needed based on daily energy usage and backup days.

Centrifuge RPM to RCF Converter

Convert centrifuge speed between RPM and RCF (relative centrifugal force in g) from rotor radius. Uses RCF = 1.118 × r × (RPM/1000)² for lab protocols.

Doppler Shift Calculator

Calculate the Doppler effect from source and observer speed. Returns observed frequency for approaching and receding motion with siren and redshift examples.

Earthquake Distance Calculator

Estimate earthquake epicenter distance from P-wave and S-wave arrival time difference using the Wadati method. Includes wave speed constants and examples.

Focal Length Equivalent Calculator

Convert camera focal lengths between full frame, APS-C (1.5x and 1.6x), MFT (2x), and 1-inch sensors. Returns equivalent field of view and angle in degrees.

Half-Life Calculator

Calculate radioactive or chemical half-life decay. Find remaining quantity, elapsed time, or half-life period from known values.

Noise Level and Safe Exposure Calculator

Compare dB levels of common sounds and calculate NIOSH daily exposure time at any level. Covers workplace, concert, traffic, and power tool noise.

Radiation Dose Comparison Calculator

Compare radiation exposure from chest X-ray (0.1 mSv), CT scan (7 mSv), and flights against the 2.4 mSv annual background dose in μSv and mSv.

Radioactive Decay (Half-Life) Calculator

Calculate radioactive decay, remaining material, and activity after a given time. Supports common isotopes with known half-lives.

Seismic Intensity Calculator

Convert between Richter, moment magnitude, and Modified Mercalli Intensity scales. Estimate peak ground acceleration and shaking intensity at any distance.

Sound Wavelength Calculator

Calculate sound wavelength in meters and cm from frequency and medium. Covers speed in air (343 m/s), water, steel, and wood with a note frequency table.

Terminal Velocity Calculator

Calculate the terminal velocity of a falling object based on mass, drag coefficient, cross-sectional area, and air density.

Battery Energy Calculator

Calculate battery energy in watt-hours and kWh from voltage and capacity. Estimate runtime at any load for phones, laptops, solar storage, and off-grid use.

Electrical Power Calculator (Ohm's Law + Power Wheel)

Enter any two of voltage, current, resistance, or power to solve for the other two using Ohm's Law. Covers all four variable combinations in the Ohm wheel.

Electricity Bill Estimator

Estimate monthly electricity bill from appliance wattage, daily usage hours, and kWh rate. Add multiple devices to see which ones cost the most to run.

Magnetic Field Calculator

Calculate magnetic field strength around a current-carrying wire using the Biot-Savart law: B = μ₀I/2πr. Returns field in Tesla and Gauss at distance r.

Projectile Motion Calculator

Calculate maximum height, range, and time of flight for a projectile. Enter launch velocity and angle to see the full trajectory.

Specific Gravity Calculator

Calculate specific gravity from substance and reference densities. Includes common material SG values and determines whether a substance floats or sinks.

Static Water Pressure Calculator

Calculate static pressure in PSI, bar, and kPa from fluid column height using P = rho x g x h. Covers water, oil, and mercury for plumbing and hydraulic design.

Torque Calculator

Calculate torque τ = F × d in Nm and ft-lb from force and lever arm, or solve for any missing variable. Returns examples for wrenches, engines, and beams.

Voltage Drop Calculator

Calculate voltage drop from wire gauge (AWG), length, and current. Shows voltage lost, percentage drop, and whether the circuit meets the NEC 3% standard.

Wavelength to Color Calculator

Convert visible light wavelength in nm to color name, hex code, and frequency in THz. Covers the full spectrum from violet (380 nm) to red (700 nm).

Wire Resistance Calculator

Calculate wire resistance from material, length, and AWG gauge using R = rL/A. Covers copper, aluminum, silver, and gold in imperial and metric units.

Acceleration Calculator

Calculate acceleration from initial velocity, final velocity, and time. Also computes distance traveled during acceleration.

Buoyancy Calculator

Calculate the buoyant force on any object using Archimedes' principle. Enter object volume, fluid density, and object density to determine float or sink.

Carbon-14 Dating Calculator

Estimate the age of an organic sample from its remaining Carbon-14 percentage. Uses the radioactive decay formula with C-14's half-life of 5,730 years.

Centripetal Force Calculator

Calculate centripetal force and acceleration for circular motion. Enter mass, velocity, and radius to find the force keeping an object in its path.

Coulomb's Law Calculator

Calculate the electric force between two charged particles using Coulomb's Law. Enter charges and distance to find the force.

Decibel Calculator

Calculate decibel difference between sound levels using dB = 10 log10(P2/P1). Converts dB to intensity ratios and perceived loudness changes.

Density Calculator

Calculate density, mass, or volume using ρ = m/V. Supports kg/m³, g/cm³, lb/ft³ — with a density reference table for metals, liquids, and building materials.

Drug Half-Life Calculator

Calculate medication remaining from dose, half-life in hours, and time elapsed. Returns concentration at each interval and time to reach 1% of original dose.

Earthquake Energy Calculator

Enter an earthquake magnitude and see the energy released in joules and TNT equivalent. Understand the power behind Richter scale numbers.

Electricity Cost / kWh Calculator

Calculate how much electricity an appliance uses per month and what it costs. Enter watts, hours per day, and your electricity rate.

Escape Velocity Calculator

Calculate the escape velocity for any celestial body from its mass and radius. Includes presets for Earth, Moon, Mars, Jupiter, and the Sun for comparison.

Force Calculator (Newton's Second Law)

Calculate force, mass, or acceleration using Newton's Second Law F=ma. Supports newtons, pounds-force, kg, m/s^2, and ft/s^2 with worked examples.

Fuel Energy Content Calculator

Calculate the energy content of gasoline, diesel, natural gas, or propane in BTU and kilojoules. Compare fuel types by energy density.

Gravity / Free Fall Calculator

Calculate free fall time and impact velocity from height, or find height from fall time. Supports both metric and imperial units.

Heat Transfer Calculator (Q = mcΔT)

Calculate heat energy transferred using mass, specific heat capacity, and temperature change. Supports joules, calories, and BTU output.

Kinetic Energy Calculator

Calculate kinetic energy KE = ½mv² from mass in kg or lbs and velocity in m/s, km/h, or mph. Returns energy in Joules, kJ, and ft·lbf for physics problems.

Lightning Distance Calculator

Calculate the distance to a lightning strike from flash-to-thunder delay. Based on 343 m/s speed of sound — shows distance in miles and km with safety tips.

Momentum Calculator

Calculate momentum from mass and velocity, or use the collision calculator to find velocities after elastic and inelastic collisions.

Noise Reduction Calculator

Calculate how much a noise barrier reduces sound levels. Enter source decibels, barrier NRC rating, and distance for the reduced dB level.

Ohm's Law Calculator

Calculate voltage, current, resistance, or power using Ohm's Law (V=IR) and Watt's Law (P=IV). Solve for any variable instantly for electronics projects.

Pendulum Calculator

Calculate pendulum period, frequency, and oscillations per minute from length. Uses T = 2pi x sqrt(L/g) with support for meters, feet, and inches.

Pipe Volume Calculator

Calculate the volume of water or fluid inside a pipe by entering diameter and length. Supports inches, feet, centimeters, and meters.

Radioactive Decay Calculator

Calculate remaining radioactive substance using N = N₀ × (1/2)^(t/t½) from initial quantity and half-life. Returns remaining mass and activity in becquerels.

Reynolds Number Calculator

Calculate the Reynolds number to determine if fluid flow is laminar or turbulent based on velocity, diameter, and viscosity.

Speed of Sound Calculator

Calculate the speed of sound in air, water, or steel at any temperature. Includes unit conversion between m/s, ft/s, mph, and km/h.

Speed, Distance & Time Calculator

Calculate speed, distance, or time when you know the other two. Supports km/h, mph, m/s, and knots — useful for driving, running, cycling, and sailing.

Thermal Expansion Calculator

Calculate linear or volumetric thermal expansion from material type and temperature change. Covers steel, aluminum, copper, glass, concrete, and wood.

Thin Lens Equation Calculator

Solve the thin lens equation 1/f = 1/do + 1/di. Enter any two of focal length, object distance, or image distance to find the third.

Time Dilation Calculator

Calculate relativistic time dilation and length contraction from Einstein's special relativity. Enter velocity as a percentage of the speed of light.

Water Flow Rate Calculator

Calculate water flow rate in GPM and LPM from pipe diameter, pressure, and length using Hazen-Williams. Covers PVC, copper, and steel pipe sizing.

Wavelength Calculator

Calculate wavelength from frequency and wave speed. Supports light (speed of light) and sound waves. Shows results in meters, nanometers, and centimeters.