Speed Distance Time Calculator
Enter any two values to solve for the third. Mix units freely.
Speed = Distance ÷ Time | D = S × T | T = D ÷ S
About this tool
Speed Distance Time Calculator
Speed Distance Time solves for whichever of the three you are missing, with multiple unit options.
How to use it
- Enter any two of speed, distance and time.
- Choose your units.
- Read the third value.
One relationship, three rearrangements
Speed equals distance divided by time. Rearranged, distance is speed multiplied by time, and time is distance divided by speed. All three questions come from a single relationship.
The part that causes errors is units. Speed in miles per hour with time in minutes gives a nonsense answer unless one is converted first, and mixing metric and imperial does the same. Keeping units consistent matters more than the arithmetic does.
When it helps
- Estimating a journey time from a distance and an expected speed.
- Working out an average speed from a completed trip.
- Calculating how far something travels in a given period.
- Checking a physics or homework answer.
Common mistakes
- Mixing units without converting, which is the single most common source of wrong answers.
- Confusing average speed with instantaneous speed. Average over a trip includes every stop.
- Averaging two speeds directly. The average speed over two equal distances at different speeds is not the mean of the two.
