Speed Converter

A 5K pace, a motorway sign and a pilot's briefing each report speed in their own unit. Runners think in minutes per kilometre, UK cameras in mph, most countries in km/h, sailors in knots. The conversion is far from academic: a '10 mph' treadmill setting is 16.09 km/h, so treating the two as roughly equal will quietly wreck a training plan. This converter shows five units side by side.

Enter values

Results

In miles per hour (mph): 6.2137
In metres per second (m/s): 2.7778
In knots (kn): 5.3996
In mach: 0.008163
In feet per second (ft/s): 9.1134
Exact factor: 1 km/h = 0.6213711922 mph

How is the Speed Converter calculated?

Enter the speed and the unit it is quoted in. Your converted speed leads the results, followed by the same velocity in metres per second, knots, Mach and feet per second, with the exact factor (1 km/h = 0.6213711922 mph) in the last row so you can repeat the sum. Zero is a legitimate value — a standing start converts cleanly to zero in every unit.

Formula

Convert through kilometres per hour: km/h = value × from factor, then target = km/h ÷ to factor. Exact factors: 1 mph = 1.609344 km/h · 1 m/s = 3.6 km/h · 1 kn = 1.852 km/h · 1 ft/s = 1.09728 km/h. Mach uses the sea-level speed of sound: 340.29 m/s, or 1,225.044 km/h at 15 °C.

Example

A 5K finished in 25 minutes is 5 ÷ (25 ÷ 60) = 12 km/h, which is 12 ÷ 1.609344 = 7.46 mph and 12 ÷ 3.6 = 3.33 m/s. On the motorway, 100 km/h is 62.14 mph — worth knowing when a rental car reads mph. A knot is 1.852 km/h, so a ship steaming at 100 kn is covering 185.2 km/h. A half marathon of 21.0975 km in two hours averages 10.55 km/h, or 6.55 mph.

Things to remember

Pace and speed are reciprocals — 5:00 min/km equals 12 km/h — so if your goal is a finish time rather than a velocity, invert before you convert. Wind, gradients and treadmill calibration all shift real-world speed too: treat these figures as exact arithmetic performed on an already approximate measurement.

Frequently Asked Questions

How do I convert kilometres per hour to mph?

Divide by 1.609344, or multiply by 0.621371 for a fast estimate. So 100 km/h is 62.14 mph, 60 km/h is 37.28 mph and 10 km/h is 6.21 mph. To reverse the direction, multiply mph by 1.609344 instead.

What speeds do people actually run at?

Easy jogging sits around 8–10 km/h (5–6.2 mph), a steady run at 12–14 km/h (7.5–8.7 mph), and elite marathon pace is close to 20 km/h (12.4 mph). Converting your treadmill number once makes those bands far less abstract.

How many knots are in one kilometre per hour?

One knot is 1.852 km/h, so divide km/h by 1.852 to get knots: 100 km/h equals 53.996 kn, normally rounded to 54. A knot is one nautical mile per hour, and the nautical mile is exactly 1,852 metres.

Why does my car show a different number in mph?

Because speedometers are calibrated for the market they were built for, and the conversion is not round: 50 km/h is 31.07 mph and 30 mph is 48.28 km/h. Imported cars, rentals and borrowed vehicles are the usual source of that particular confusion.