Speed Distance Time Calculator
Choose what to find, enter the other two values and get speed, distance or time, with km/h and mph conversions.
What this tool does
Speed, distance and time are linked by speed = distance ÷ time. Choose which one you want to find, enter the other two and the units, and the calculator solves it. 150 km in 2 hours is 75 km/h; at 60 km/h, 150 km takes 2.5 hours. Results are also shown in km/h, mph and m/s.
Solves speed = distance ÷ time, distance = speed × time or time = distance ÷ speed.
Converts to km/h, mph and m/s and formats time as hours, minutes and seconds.
How to use it
- Choose what to find.
- Enter the two known values.
- Choose the distance unit and the time unit.
- Read the result and the conversions.
Why use this calculator
Solves for speed, distance or time from the other two, in kilometres, miles or metres and hours, minutes or seconds. Planning a journey, a run or a delivery comes down to these three numbers. It is easy to mix units - minutes with kilometres per hour, say - so a tool that keeps units straight prevents mistakes.
Why we built it
We built this calculator to solve for speed, distance or time from the other two, in kilometres, miles or metres and hours, minutes or seconds. The pace calculator is tuned for runners, and the speed converter changes units.
Handy alongside this: the Acceleration Calculator.
Who this tool is for
- Drivers, cyclists and runners planning journeys
- Students solving motion problems
- Pilots and sailors doing rough estimates
When to use it
- Estimating journey or travel time.
- Working out average speed over a trip.
- Planning a run, ride or flight.
- Physics and maths homework.
How it works
Speed = distance ÷ time; distance = speed × time; time = distance ÷ speed. The three units must agree: kilometres with hours gives km/h, miles with hours gives mph, metres with seconds gives m/s.
Internally everything is converted to metres and seconds so that km/h, mph and m/s are all exact conversions of the same speed.
This gives an average speed. Stops, traffic and changing speed are not modelled.
A worked example
These are the values the calculator opens with, so you can see exactly what it does with them. Change any value on the page and the result updates; the figures below come from the same calculation.
| Input | Value |
|---|---|
| Find | Speed |
| Speed | 60 |
| Distance | 150 |
| Time | 2.5 |
| Distance unit | Kilometres |
| Time unit | Hours |
With those inputs, the calculator returns:
- Speed: 60 km/h
- Speed: 60 km/h
- Distance: 150 km
- Time: 2.5 h (2h 30m 0s)
- Speed in km/h: 60
- Speed in mph: 37.282
- Speed in m/s: 16.667
What you give it, and what you get back
| Item | Details |
|---|---|
| Find | Speed, distance or time. |
| Known values | Enter the other two, greater than 0. The one being found is ignored. |
| Units | Kilometres, miles or metres; hours, minutes or seconds. |
| Result | The answer, plus speed in km/h, mph and m/s and time as h/m/s. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| "Enter the two known values" | A required value is 0 or empty. | Fill in the two you know. |
| Speed looks wrong | Time was entered in minutes but the unit is hours. | Match the time unit. |
| Time is a decimal | Decimal hours, such as 2.5. | See the h/m/s line: 2.5 h is 2 h 30 m. |
| Real journey took longer | Stops and traffic. | Use a lower average speed. |
Assumptions and limitations
- Average speed over a whole trip only.
- Constant units: no mixed distance units.
- No acceleration or varying speed.
Frequently asked questions
How do I calculate average speed?
Divide the total distance by the total time.
How do I calculate how long a journey takes?
Divide the distance by your average speed.
How do I convert km/h to mph?
Multiply by 0.621371, or divide by 1.609344.
What is the speed distance time formula?
Speed = distance ÷ time, which rearranges to distance = speed × time and time = distance ÷ speed.
Why is my answer in decimal hours?
Because the time unit is hours. The h/m/s line shows it as hours, minutes and seconds.
Is it free and private?
Yes. It runs in your browser.