Speed Calculator

Calculate and convert speed between different units

About Speed Calculator

A speed calculator converts between units of speed — mph, km/h, m/s, and knots — and can also work out average speed from a distance and a travel time. It's used for anything from converting a speed limit sign to checking pace during a run or flight.

Formula

Speed = Distance / Time — and 1 mph = 1.60934 km/h = 0.44704 m/s = 0.86898 knots

How It Works

To convert a speed, enter the value and choose the unit you're converting from and to
The calculator multiplies your value by the conversion factor between those two units
To find average speed, enter a total distance and total time instead, and it divides distance by time
Results update instantly as you change any input

Examples

Calculation	Expression	Result
mph to km/h	60 mph	96.56 km/h
km/h to mph	100 km/h	62.14 mph
m/s to mph	10 m/s	22.37 mph
Knots to mph	20 knots	23.02 mph
Average speed	150 mi ÷ 2.5 hr	60 mph

Tips

1 mph = 1.60934 km/h, so multiply mph by 1.60934 to get km/h, or divide km/h by 1.60934 to get mph
1 m/s = 3.6 km/h — useful for physics problems given in meters per second
Knots are used in aviation and marine navigation: 1 knot = 1.15078 mph = 1.852 km/h
Average speed for a round trip is total distance divided by total time, not the simple average of the two speeds

Frequently Asked Questions

How do I convert mph to km/h?

Multiply the speed in mph by 1.60934. For example, 60 mph × 1.60934 = 96.56 km/h.

How do I convert km/h to mph?

Divide the speed in km/h by 1.60934, or multiply by 0.62137. For example, 100 km/h × 0.62137 = 62.14 mph.

How do I calculate average speed?

Divide total distance traveled by total time taken: Average Speed = Distance / Time. For example, 150 miles in 2.5 hours = 60 mph.

Is average speed just the average of my fastest and slowest speed?

No — average speed is always total distance divided by total time. If you drive 60 mph for one hour and 40 mph for one hour, your average speed is 50 mph (100 miles / 2 hours), but if you instead drove equal distances at those two speeds, the average would be lower than 50, because you spend more time at the slower speed.

What is a knot in mph?

1 knot equals 1.15078 mph (or 1.852 km/h). Knots are the standard speed unit in aviation and maritime navigation, based on nautical miles per hour.