Amateur Radio Calculators
Free amateur radio (HAM) calculators: antenna length, path loss, SWR ratio, repeater coverage, impedance matching, and more ham radio tools.
Ham Radio Antenna Q and Bandwidth Calculator
Calculate antenna bandwidth from Q-factor and resonant frequency. Get -3dB bandwidth and 2:1 SWR bandwidth for HF, VHF, and UHF antenna designs.
Quarter-Wave Vertical Antenna Calculator
Calculate quarter-wave vertical antenna length and ground radial dimensions for any amateur radio frequency. Includes loading coil for shortened verticals.
Yagi Antenna Calculator
Calculate Yagi antenna element lengths and spacing for 3, 4, or 5 element designs. Find driven element, reflector, and director dimensions for any band.
Antenna Gain Calculator (dBi)
Calculate antenna gain in dBi and dBd, effective radiated power, and compare dipole, Yagi, and directional antenna types for ham radio and RF link budgets.
Coax Cable Signal Loss Calculator
Calculate coaxial cable signal attenuation in dB from cable type, length, and frequency. Covers RG-8, RG-58, RG-213, and LMR-400 for HF, VHF, and UHF.
Dipole Antenna Length Calculator
Calculate dipole antenna lengths at any frequency using 468/f(MHz). Returns total and per-element dimensions in feet and meters for HF, VHF, and UHF bands.
Ham Radio Power Supply Sizing Calculator
Calculate the correct DC power supply current rating for an amateur radio station from transmitter power, accessories, and duty cycle in amperes.
Ham Radio Repeater Offset Calculator
Calculate repeater offset and TX/RX frequency for 2m, 70cm, and 23cm ham radio bands. Returns standard IARU offsets for North American and European plans.
Ham Radio Wire Antenna Length Calculator
Calculate wire length for dipole, inverted-V, and end-fed half-wave antennas from MHz. Returns each leg and total using the 468/f formula with velocity factor.
dBm to Watts Converter
Convert between dBm and watts for amateur radio power levels. Includes common reference points and transmitter power chart.
Free-Space Path Loss Calculator
Calculate free-space path loss (FSPL) between two radio stations. Enter frequency and distance to get signal attenuation in dB.
Repeater Coverage Calculator
Estimate the radio horizon and coverage radius of a ham radio repeater based on antenna height. Uses line-of-sight radio propagation formula.
SWR and Reflected Power Calculator
Calculate Standing Wave Ratio (SWR) from impedance mismatch, and find the percentage of power reflected back. Essential for antenna tuning.
Wavelength and Frequency Calculator
Convert between radio frequency and wavelength. Calculate quarter-wave and half-wave antenna dimensions for any amateur radio band.