Speed Calculator
What the speed calculator does
The speed calculator divides a distance in kilometres by a time in hours and returns average speed in kilometres per hour. Enter the two values and press Calculate. It answers the everyday question “how fast was I going, on average?” for journeys, runs, rides and deliveries.
The formula
speed = distance ÷ time
With distance in km and time in hours the result is km/h. The same formula works in any consistent pair of units: metres and seconds give m/s, miles and hours give mph. Because the tool takes hours, convert minutes first: 45 minutes is 0.75 h, and 1 h 20 min is 1.333 h.
Worked examples
| Journey | Distance | Time | Average speed |
|---|---|---|---|
| Motorway drive | 240 km | 2.5 h | 96 km/h |
| City commute | 12 km | 0.6 h (36 min) | 20 km/h |
| 10 km run | 10 km | 0.833 h (50 min) | 12 km/h |
| Cycling club ride | 80 km | 3.2 h | 25 km/h |
| Flight | 1,800 km | 2.25 h | 800 km/h |
Converting the result
| km/h | mph | m/s | min per km |
|---|---|---|---|
| 5 | 3.1 | 1.39 | 12:00 |
| 10 | 6.2 | 2.78 | 6:00 |
| 15 | 9.3 | 4.17 | 4:00 |
| 50 | 31.1 | 13.9 | 1:12 |
| 100 | 62.1 | 27.8 | 0:36 |
Divide km/h by 1.609 for mph and by 3.6 for m/s. Runners usually prefer pace, minutes per kilometre, which is 60 divided by km/h; the pace to speed converter switches between the two.
Average versus instantaneous speed
The calculator gives the average over the whole trip, including stops if they are inside the time you enter. A 240 km drive that takes 2.5 h door to door averages 96 km/h even if the car cruised at 120 km/h and spent 30 minutes at a service station. To find the moving average, subtract the stopped time first. A speedometer shows instantaneous speed, which is the average over a very short interval.
Speed versus velocity
Speed is a scalar: it has size but no direction, and it is based on the distance actually travelled. Velocity is a vector based on displacement, the straight-line change in position, so a round trip has an average velocity of zero. For physics problems that need the sign or direction, use the velocity calculator.
Rearranging for time or distance
The same relation gives time = distance ÷ speed and distance = speed × time. At 90 km/h, 315 km takes 3.5 h; at 4.5 km/h a walker covers 9 km in 2 h. The time calculator helps add the resulting hours and minutes to a departure time, and the flight time calculator applies typical cruising speeds to air routes.
Common mistakes
- Entering minutes in the hours field. 90 minutes must be entered as 1.5.
- Mixing miles and kilometres. A 50-mile trip is 80.5 km. Convert the distance before dividing, or read the result as mph.
- Using clock time instead of elapsed time. Leaving at 9:40 and arriving at 11:10 is 1.5 h, not 1.7.
- Forgetting stops. Decide whether you want overall or moving average speed and enter the matching time.
Related tools
The speed converter covers knots and feet per second. The fuel consumption per mile calculator combines distance with fuel use, and the acceleration converter and projectile motion calculator deal with changing speed.
External references
Frequently asked questions
How do I enter a time like 2 hours 15 minutes?
Divide the minutes by 60 and add to the hours: 2 + 15/60 = 2.25.
Can I get the answer in mph?
Enter the distance in miles and the time in hours. The label will still say km/h, but the number is miles per hour.
What is a typical walking speed?
About 5 km/h on flat ground, or 1.4 m/s. Brisk walking is 6 km/h; hiking with a pack on hills often drops to 3 to 4 km/h.
Why is my average speed lower than I expected?
Traffic lights, junctions and stops count against you. Even on a motorway, the door-to-door average is usually 10 to 20% below cruising speed.
Does the tool work for very small distances?
Yes, but km and hours are awkward for short sprints. Enter metres and seconds instead and read the answer as m/s.