Calculate speed, distance, or time — enter any two values and find the third.
This tool calculates speed, distance, or time when the other two values are known, using the fundamental relationship between these three quantities. It's useful for physics problems, travel planning, running and cycling pace, and understanding vehicle speeds.
Speed = Distance ÷ Time. Rearranged: Distance = Speed × Time, and Time = Distance ÷ Speed. Common units include km/h, mph, and m/s, with conversions available between them.
Enter any two of the three values (speed, distance, or time), and the calculator solves for the missing third value.
Example 1: Traveling 150 km in 3 hours means an average speed of 150 ÷ 3 = 50 km/h.
Example 2: At a speed of 60 mph, traveling for 2.5 hours covers 60 × 2.5 = 150 miles.
What's the difference between average speed and instantaneous speed? Average speed is the total distance divided by total time over an entire trip, while instantaneous speed is the speed at one specific moment — a speedometer shows instantaneous speed, while trip calculations typically use average speed.
How do I convert between mph and km/h? Multiply mph by 1.60934 to get km/h, or multiply km/h by 0.62137 to get mph.
Why does average speed calculation ignore stops and slowdowns? Average speed is simply total distance divided by total elapsed time, so it automatically accounts for stops within the "time" value, even though it doesn't show the variation throughout the trip.
What is m/s used for? Meters per second is the standard scientific unit for speed, commonly used in physics calculations and engineering rather than everyday travel contexts.
Can this calculator help estimate travel time for a trip? Yes, if you know the distance and an estimated average speed, you can calculate expected travel time, which is useful for trip planning.