Use this speed calculator to solve for average speed, distance, or elapsed time when you know the other two values. Enter each value in the unit you actually have; the linked fields convert mixed units and fill the missing value.
How speed, distance, and time fit together
Speed, distance, and time use one relationship. Average speed equals total distance divided by total elapsed time. Rearranging that equation gives Distance = Speed × Time and Time = Distance / Speed, so the same three linked fields can solve whichever value is missing.
Leave the value you want to find blank. The calculator fills it automatically.
Select the matching unit for each plain value. For compound elapsed time, enter h:mm or h:mm:ss.
The answer describes the whole distance and elapsed time, not the speed at one instant.
Choose the values and units you actually have
Distance may come from a map, odometer, course measurement, or problem statement. Time should cover that same distance. If you want moving speed, exclude stops; if you want whole-trip speed, include them.
Choose the unit beside each plain value independently. A distance in mi can be paired with time in min and the answer can be shown in . You can also enter elapsed time as h:mm or h:mm:ss; for example, 1:30 means 1 h 30 . The engine converts everything before it calculates, so do not convert the numbers by hand.
Worked example: 120 miles in 2 hours
Distance = 120 mi
Time = 2 h
Speed = Distance / Time
Speed = 120 / 2 h
Speed = 60
The same speed is 96.56 or 26.82 .
What average speed tells you
Average speed is total distance divided by total elapsed time. It remains useful when the speed changed during the trip, but it does not reveal the fastest or slowest moment. Speed is a scalar; velocity also includes direction and uses displacement, so this calculator does not calculate directional velocity.
Do not take a simple arithmetic mean of two segment speeds unless the time spent at each speed is equal. Add the segment distances and divide by the combined time instead. Use the solved value for planning or checking, with room for real stops and changing conditions.
When you need a different speed calculator
Use a running pace calculator when the required output is minutes per mile or minutes per kilometer. Use a vehicle-speed calculator when the known values are engine , gear ratio, and tire size. Use an internet speed or download-time calculator for Mbps or Gbps. Those tasks use different quantities and do not belong in this three-field motion calculator.