Quick answer: Speed is distance divided by time: 120 km in 1 hour 30 minutes (1.5 h) is 120 ÷ 1.5 = 80 km/h.
How it's calculated
Average speed v = d ÷ t. Rearranged, distance d = v × t and time t = d ÷ v. Time is entered in hours, minutes and seconds and converted to decimal hours (30 minutes = 0.5 h).
The answer is the average over the whole trip, including slow and fast stretches. Stops count too if you include them in the time.
Conversions: 1 mile = 1.609344 km exactly, and 1 m/s = 3.6 km/h. Pace is the time per kilometre, 60 ÷ speed in km/h minutes.
Worked examples
- 120 km in 1 h 30 min: 120 ÷ 1.5 = 80 km/h
- Riyadh to Dammam, about 400 km at 120 km/h: t = 400 ÷ 120 = 3.333 h = 3 h 20 min
- 2 h 15 min at 100 km/h: d = 100 × 2.25 = 225 km
Frequently asked questions
What is the formula for speed?
Speed = distance ÷ time. Distance = speed × time, and time = distance ÷ speed.
How do I convert minutes to hours?
Divide by 60: 45 minutes is 0.75 hours. The calculator does this for you when you fill in hours and minutes.
How do I convert km/h to m/s?
Divide by 3.6: 90 km/h = 25 m/s. To go from m/s to km/h, multiply by 3.6.
How long does 120 km take at 80 km/h?
An hour and a half.
How do stops affect average speed?
Count them in the total time. Drive 120 km in 90 minutes, stop for half an hour, and your average for the trip drops to 60 km/h.
How do I work out running pace?
Divide 60 by your speed in km/h. At 12 km/h you're running 5-minute kilometres.