How to use it
- Choose what to find: speed, distance or time.
- Enter the distance and pick its unit.
- Enter the time as h:mm:ss or the speed and its unit.
- Read the result and the unit conversions.
The speed formula
Speed = distance ÷ time
Rearranged:
- Distance = speed × time
- Time = distance ÷ speed
Pick which value you want, enter the other two, and the calculator does the rest, converting between units automatically. Time is entered as hours:minutes:seconds (1:30:00) or minutes:seconds (45:00). Everything runs in your browser.
Examples
- Average speed: 120 miles in 1 hour 30 minutes = 120 / 1.5 = 80 mph.
- Distance: 60 mph for 2.5 hours = 150 miles.
- Travel time: 300 miles at 65 mph = 4.615 hours ≈ 4 h 37 min.
- Running pace: a 26.2-mile marathon in 4:00:00 is about 6.55 mph, a pace of roughly 9:09 per mile.
The result shows the main answer in mph (or miles) plus km/h, m/s and other units.
Speed unit conversions
| Unit | In mph |
|---|---|
| 1 km/h | 0.6214 mph |
| 1 m/s | 2.2369 mph |
| 1 ft/s | 0.6818 mph |
| 1 knot | 1.1508 mph |
Going the other way: 1 mph = 1.609 km/h = 0.447 m/s = 1.467 ft/s. A useful shortcut: 60 mph is exactly 88 ft/s.
Speed in physics problems
In physics, speed is usually expressed in meters per second. Convert km/h to m/s by dividing by 3.6, and mph to m/s by multiplying by 0.447. A car at 65 mph is moving about 29 m/s, or roughly 95 feet every second, which is why following distance matters: at that speed a 2-second gap is about 190 feet.
Remember that speed has no direction; velocity does. For an object that speeds up or slows down, this calculator gives the average over the whole interval, not the speed at a particular moment.
Average speed vs. average of speeds
Average speed is total distance divided by total time, which is not the same as averaging the speeds.
Example: you drive 60 miles at 30 mph and then 60 miles at 60 mph. The first leg takes 2 hours, the second 1 hour. Average speed = 120 miles / 3 hours = 40 mph, not 45. You spend more time at the slower speed, so it counts for more.
The calculator always works from totals, so stops and slowdowns are included if you use the total trip time.
Running and cycling pace
Runners usually talk about pace (minutes per mile) rather than speed. Pace = time ÷ distance.
| Speed | Pace per mile |
|---|---|
| 5 mph | 12:00 |
| 6 mph | 10:00 |
| 7.5 mph | 8:00 |
| 10 mph | 6:00 |
Enter your race distance and finish time to see both. For a 5K (about 3.107 miles) in 28:00, you averaged about 6.66 mph, roughly a 9:01 pace. A 10K in 55:00 works out to about 6.78 mph, or 8:51 per mile.
Common mistakes
- Entering 1.30 for an hour and a half. Use 1:30:00 (or 1.5 hours as 90:00).
- Mixing units. Distance in kilometers with speed in mph gives wrong results unless you pick the right units in each field.
- Ignoring stops. A trip planner's driving time does not include gas and food breaks.
For fuel costs on your trip, use the gas mileage calculator.
Frequently asked questions
How do I calculate average speed?
Divide the total distance by the total time. 120 miles in 1.5 hours is 80 mph.
How long does it take to drive 300 miles at 65 mph?
About 4 hours 37 minutes of driving, not counting stops.
How do I convert mph to km/h?
Multiply by 1.609. 60 mph is about 96.6 km/h.
How do I enter time?
As h:mm:ss (1:30:00), mm:ss (45:00), or a number of seconds.
Can I calculate running pace?
Yes. Find speed from your distance and time; the result includes your pace per mile.
Last updated: November 12, 2026