Speed Calculator
Find speed, distance or time from the other two, or the true average speed of a trip, with pace for runners and cyclists. For road speed from rpm and gearing, use the gear ratio calculator.
Press Calculate to print your slip
Theoretical results. Real trips add stops, traffic and tire slip.
Need a quick unit switch? Open the converter
On this page
Four calculations in one
Find speed from distance and time, distance from speed and time, or time from distance and speed. Work out the true average speed of a trip with slow and fast parts, and get your pace per mile or kilometer.
What you need
- Two of three
- Any two of distance, time and speed, in miles, kilometers or meters.
- For average speed
- The distance and speed of each part of the trip.
What you get
- The answer in mph, km/h, m/s and knots
- Pace per mile and per kilometer for runners and cyclists
- The true average speed, and how far off a simple average would be
The formulas
Speed
speed = distance ÷ time
Distance
distance = speed × time
Time
time = distance ÷ speed
Average speed
total distance ÷ total time
- Time in minutes
- Divide by 60 to get hours before you divide distance by time.
- Hours
- 2 h 30 min is 2.5 hours; 45 minutes is 0.75 hours.
- Units
- 1 mph = 1.609 km/h = 0.447 m/s = 0.869 knots.
- Pace
- Time per mile or kilometer: the inverse of speed.
Worked example: 150 miles in 2 hours 30 minutes is 150 ÷ 2.5 = 60 mph.
Short distances work the same way. A quarter mile at a steady 65 mph takes 0.25 ÷ 65 hours, or about 14 seconds; at any speed it is 900 divided by mph. See how long a quarter mile is for the full table.
The average speed trap
Drive 60 miles at 30 mph, then 60 miles back at 60 mph. The average of the two speeds is 45 mph, but the trip really averaged 40 mph: the slow half took 2 hours and the fast half only 1, so you spent most of the time going slowly.
That's why average speed is always total distance divided by total time. The Average speed mode shows both numbers so you can see the gap.
Speed from rpm and gears
Road speed from engine rpm, gear ratios, final drive and tire size now has its own tool. The gear ratio calculator shows speed in every gear at once, cruising rpm at any speed, and what a new rear-end ratio or tire size changes, with presets for popular cars.
Speed in every gear
Enter your gear ratios, final drive and tire size, or start from a preset.
Gear Ratio CalculatorExample calculations
| Question | Mode | Answer | Also |
|---|---|---|---|
| 150 miles in 2 h 30 minRoad trip | Speed | 60 mph | 96.6 km/h |
| 10 km in 50 minutesRunning | Speed | 12 km/h | 5:00 per km |
| 400 km at 100 km/hMotorway drive | Time | 4 h 00 min | 248.5 miles |
| Marathon in 4 hours26.2 miles | Speed | 6.55 mph | 9:10 per mile |
| 60 mi at 30 mph, then 60 mi at 60 mphTwo-part trip | Average speed | 40 mph | Not 45 mph |
How to use it
Pick what to find
Speed, distance, time or average speed.
Choose units
Miles, kilometers or meters, and mph, km/h, m/s or knots.
Enter what you know
Time can be any mix of hours, minutes and seconds.
Read the slip
The answer in every unit, plus pace or trip totals.
Sources and method
Speed, distance and time are linked by speed = distance ÷ time, and the unit conversions use exact factors (1 mile = 1.609344 km). Speed from rpm uses the gear ratio, final drive and tire size you enter.
Updated September 2026. Built and checked by the 0-60calc Team. Found a mistake? Tell us and we will check it against the source.
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Questions people ask
How do you calculate speed?
Divide the distance by the time. 120 miles in 2 hours is 120 ÷ 2 = 60 mph. If the time is in minutes, divide the minutes by 60 first: 10 km in 50 minutes is 10 ÷ 0.833 = 12 km/h.
What is the formula for average speed?
Total distance divided by total time. It is not the average of the speeds: driving 60 miles at 30 mph and 60 miles at 60 mph averages 40 mph, not 45, because you spend twice as long on the slow half.
How do I calculate time from speed and distance?
Divide the distance by the speed. 150 km at 100 km/h takes 1.5 hours, which is 1 hour 30 minutes.
How do I work out distance from speed and time?
Multiply the speed by the time. 65 mph for 3 hours 15 minutes covers 65 × 3.25 = 211 miles.
How do I find my car's speed from engine rpm?
Multiply rpm by the tire diameter in inches, then divide by the gear ratio times the final drive ratio times 336. The gear ratio calculator does it for every gear at once.
What is the difference between speed and velocity?
Speed is how fast something moves. Velocity is speed in a given direction. For a car on a road, the numbers are the same; the difference matters in physics problems.