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Speed Calculator
Speed, distance and time are linked by one formula, so any one of them can be found from the other two. Choose what you want to calculate and enter the other two values in whatever units you have.
- Speed
- 60 mph
- Distance
- 150 mi
- Time
- 2 h 30 min
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Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Choose whether to calculate speed, distance or time.
- Enter the two values you know, picking a unit for each.
- Read the answer, and switch the result units below it if you need knots, meters per second or kilometers.
Worked examples
Average speed for 150 miles in 2.5 hours
- Answer
- 60 mph (96.56 km/h)
- Speed
- 60 mph
Distance covered at 55 mph for 3 hours
- Answer
- 165 mi (265.54 km)
- Distance
- 165 mi
Time to cover 100 miles at 40 mph
- Answer
- 2 h 30 min
- Time
- 2 h 30 min
Watch the units
The formula only works when the units agree. Miles divided by hours gives miles per hour; if your time is in minutes, convert it first (45 minutes is 0.75 hours) or switch the time unit here to minutes.
Useful conversions: 60 mph = 96.56 km/h = 88 ft/s = 26.82 m/s. 100 km/h = 62.14 mph. 1 knot = 1.151 mph = 1.852 km/h.
Average speed is not the average of speeds
Average speed is total distance divided by total time. If you drive 60 miles at 30 mph and 60 miles back at 60 mph, you cover 120 miles in 3 hours, an average of 40 mph, not 45. The slower leg counts for more because you spend longer on it.
Questions people ask
How do I calculate average speed?
Divide the total distance by the total time. 150 miles in 2.5 hours is 60 mph.
How far will I travel at 55 mph for 3 hours?
165 miles (55 × 3), which is about 265.5 km.
How long does it take to go 100 miles at 40 mph?
2 hours 30 minutes: 100 ÷ 40 = 2.5 hours.