Speed, Distance & Time Calculator
Calculate speed, distance, or time given the other two values.
Supports multiple units.
Speed, velocity, and distance are the three pillars of kinematics — the branch of physics that describes motion. These three quantities are bound by a set of simple but powerful formulas that apply everywhere from a Sunday drive to spacecraft navigation.
The three core formulas:
- Speed = Distance ÷ Time →
S = D / T - Distance = Speed × Time →
D = S × T - Time = Distance ÷ Speed →
T = D / S
Variable definitions:
- S = Speed (how fast you are moving, regardless of direction)
- D = Distance (total path length traveled)
- T = Time (duration of travel)
- Velocity = Speed with a direction (e.g., 60 mph north). In everyday problems, speed and velocity are used interchangeably.
Worked example: A car drives 240 miles from New York to Boston. The trip takes 4 hours. Speed = 240 / 4 = 60 mph
Now reverse it: if a train travels at 90 km/h for 2.5 hours: Distance = 90 × 2.5 = 225 km
Unit reference table:
| System | Speed Unit | Distance | Time |
|---|---|---|---|
| Imperial | mph | miles | hours |
| Metric | km/h | kilometers | hours |
| Science | m/s | meters | seconds |
| Maritime | knots | nautical miles | hours |
Conversion quick facts:
- 1 mph = 1.609 km/h
- 1 knot = 1.852 km/h
- 60 mph = 88 feet per second
- Speed of sound at sea level ≈ 767 mph (1,235 km/h)
- Speed of light ≈ 670,616,629 mph (299,792 km/s)
Real-world benchmarks:
- Walking pace: ~3 mph (5 km/h)
- Cycling: ~12–15 mph (19–24 km/h)
- Highway driving: 60–75 mph (97–121 km/h)
- Commercial aircraft: ~575 mph (925 km/h)
This calculator solves for any one of the three values when you provide the other two. Select your preferred unit system, enter the known values, and the result updates instantly.