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Speed, distance and time calculator

  

Average speed over the whole trip, with no stops. Distance is in kilometres, speed in km/h and time in hours and minutes.

Find the

km

Speed

48.00 km/h

120.00 km in 2 h 30 min.

Speed in m/s
13.33
Speed in mph
29.83
Minutes per km
1.25

Three quantities, one relationship

Speed, distance and time are tied by one equation, and every question about them is a rearrangement. If you know any two, the third follows.

A road trip of 120 km that takes 2 hours 30 minutes works out to 120 ÷ 2.5 = 48 km/h. That is 13.33 m/s, or about 29.8 miles an hour. At that average you take 1.25 minutes for each kilometre. If you wanted to arrive in 2 hours, you would need to average 60 km/h.

The usual trap is the unit. A time of 2 hours 30 minutes is 2.5 hours, not 2.30. And a speed in km/h does not match a distance in metres.

Average speed also hides stops. A journey with a 30-minute break should use the total time if you want the arrival time, but only the moving time if you want to know the driving speed.

Sources

What this calculator does not account for

  • Stops, traffic and changes in speed.
  • Acceleration and braking.
  • Differences between road and straight-line distance.

How this is calculated

Formula: The speed triangle

speed =distance ÷ time; distance =speed × time; time =distance ÷ speed

What the symbols mean

  • speedAverage speed in km/h.
  • distanceKilometres travelled.
  • timeHours, with minutes as a fraction of an hour.

Good to know

  • To go from km/h to m/s, divide by 3.6.
  • For runners, minutes per kilometre is 60 ÷ speed. See the pace calculator.

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Worked examples

Each example is worked out by the same code as the calculator above.

120 km in 2 hours 30 minutes

48 km/h, which is 13.33 m/s or 29.8 mph.

Embed this calculator

The frame shows the tool only.

<iframe src="/embed/speed-distance-time-calculator" title="Speed distance time" width="100%" height="720" style="border:0;max-width:42rem" loading="lazy"></iframe>

Questions

How do I convert km/h to m/s?

Divide by 3.6. So 72 km/h is 20 m/s.

Is average speed the same as the speed shown on the dial?

No. Average speed counts stops and slow patches, so it is lower than your cruising speed.

How do I convert 2 hours 30 minutes to hours?

30 minutes is 0.5 hours, so it is 2.5 hours.

Does this work for trains and flights?

Yes, as long as you use the average speed over the whole trip, including stops.