Speed Distance Time Calculator
Distance, speed, time — pick the missing one.
Speed Distance Time Calculator
Solve for the missing value in a journey, with the result also shown as a clock time and a running pace.
Time is entered in decimal hours: 1 hour 30 minutes is 1.5. The result also shows hours and minutes, and a pace per kilometre for running or walking.
1 h 15 min
Journey time
- Distance
- 100 km
- Speed
- 80 km/h
- Time
- 1.25 h
- Pace
- 0:45 /km
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What This Calculator Does
The Speed Distance Time Calculator solves the three-way relationship between distance, average speed, and journey time. Tell it which two you know and it returns the third, along with the time in hours and minutes and the equivalent running pace.
How It Works
Distance equals speed multiplied by time, so time is distance divided by speed and speed is distance divided by time. The calculator keeps everything in kilometres and hours internally, then presents the answer in the unit that makes sense for the question, including a minutes-per-kilometre pace for walking and running.
Example
A 100 km drive at an average of 80 km/h takes 1.25 hours, which is 1 hour 15 minutes. The same journey at 100 km/h takes exactly 1 hour. Running 10 km in 50 minutes is an average of 12 km/h, or a pace of 5:00 per kilometre.
Formula
time = distance ÷ speedspeed = distance ÷ timedistance = speed × timepace (min/km) = 60 ÷ speed (km/h)Reading the Results
Journey time
Elapsed time at a constant average speed. Real journeys include stops, traffic, and speed changes, so add a margin for anything time-critical.
Pace
Minutes per kilometre, the unit runners and walkers use. It is the reciprocal of speed, so a faster speed means a smaller pace number.
Sources and References
NIST Special Publication 811 — Guide for the Use of the SI
Kilometre, hour, and derived speed units
Defines the units and the relationship between them.
ISO 80000-3 — Quantities and units: space and time
Speed and velocity definitions
Confirms that average speed is distance divided by elapsed time, not an average of instantaneous speeds.
UK Highway Code — Speed limits
Practical context for average journey speeds
A reminder that legal limits are not average speeds; traffic, stops, and road type all lower the real figure.
References identify the method or data behind this calculator. Where a standard or tariff changes, the current edition applies, and the assumptions stated above take precedence over a remembered figure.
Frequently Asked Questions
Is average speed the same as the speed shown on the dashboard?
No. Average speed is total distance divided by total time, including stops. If you drive 100 km in 90 minutes with a 15-minute break, the average is about 67 km/h even though the car was doing 100 km/h on the motorway.
How do I enter 1 hour 30 minutes?
Use decimal hours: 1.5. To convert minutes to a decimal, divide by 60, so 45 minutes is 0.75 hours and 20 minutes is 0.33 hours. The result is also shown in hours and minutes so you can check it.
Why is the pace in minutes per kilometre?
Because that is the convention for running and walking almost everywhere outside the US. If you need minutes per mile, note that one mile is 1.609 km, so the pace per mile is the pace per kilometre multiplied by 1.609.
Can I use this for a flight or a boat trip?
Yes, as long as the distance and speed use the same units. It assumes a constant speed over the whole distance, so it will be approximate for anything affected by wind, current, or intermediate stops.