About the Speed Calculator
This tool computes average speed from the two quantities everyone already measures: how far something traveled and how long that took. It applies the standard kinematics formula Speed = Distance ÷ Time and reports the answer in the four speed units people ask for most — miles per hour, kilometers per hour, meters per second, and knots — so you only have to enter your numbers once.
The formula
Speed is defined as distance covered per unit of time: v = d / t. To make the units agree, the calculator first converts your distance to meters and your time to seconds using standard conversion factors (1 mile = 1,609.344 m, 1 km = 1,000 m, 1 foot = 0.3048 m; 1 hour = 3,600 s, 1 minute = 60 s), divides to get meters per second, and then converts that single speed value into mph, km/h, and knots using fixed multipliers (1 m/s = 2.236936 mph = 3.6 km/h = 1.943844 knots).
Average speed versus instantaneous speed
What this calculator returns is average speed — total distance divided by total elapsed time, including any stops, slowdowns, or traffic along the way. That is different from instantaneous speed, the reading on a speedometer at one specific moment, which can be higher or lower than the average at any point in the trip. A road trip that covers 240 miles in 5 hours averages 48 mph even if the car spent part of that time stopped for fuel and part of it at 70 mph on the highway.
Common reference speeds
- Walking: about 3–4 mph (4.8–6.4 km/h)
- Running (recreational): about 6–10 mph (10–16 km/h)
- Cycling: about 12–18 mph (19–29 km/h)
- Urban/city driving: roughly 25–45 mph (40–72 km/h)
- Highway driving: roughly 55–75 mph (89–121 km/h)
- Commercial jet cruise: roughly 460–575 mph, commonly expressed in knots (about 400–500 knots)