Mph to kph converter, miles per hour in kilometres per hour.

To convert mph to kph, multiply by 1.609344. So 60 mph is 96.56 km/h, 30 mph is 48.28 km/h and 70 mph is 112.65 km/h. The factor is exact, because the international mile is defined as 1,609.344 metres.

How to use the converter

1. Type the amount in the Miles per hour (mph) box. A decimal such as 2.5 or a fraction such as 3/4 works.
2. The big result shows Kilometers per hour (km/h). Use Decimals in the side column to fix the number of places.
3. The cards under the result give the same speed in other units.
4. Type in the second box, or press the swap button, to convert kilometers per hour to miles per hour instead.
5. Click a row in Common values to load it. Copy result, Copy link, Copy table and Print chart keep the answer. Start again resets the box.

Why the factor is exact

NIST SP 811 gives 1 mile per hour = 1.609 344 km/h, as a stated factor. A mile is 1,609.344 m and a kilometre is 1,000 m, so 1,609.344 ÷ 1,000 = 1.609344 with nothing left over.

Quick ways to estimate

Multiply by 1.6, which is 0.56 percent low: 50 mph × 1.6 = 80 km/h, against the true 80.47. Or multiply by 8 and divide by 5: 50 × 8 = 400, ÷ 5 = 80. For a closer guess, add 60 percent and a bit more: 50 + 30 = 80, plus 0.47.

Mph to kph, 5 to 100

Worked examples

• A 55 mph limit. 55 × 1.609344 = 88.51 km/h.
• A 75 mph limit. 120.7 km/h.
• A 5 mph walking pace. 8.047 km/h.
• A 3 hour drive at 65 mph. 195 miles, which is 313.8 km. At 104.61 km/h for 3 hours that agrees.
• Back the other way. 100 km/h = 62.14 mph.

Treadmill and running pace

A treadmill may show km/h while a road sign shows mph, and a runner thinks in minutes per mile or per kilometre. The Treadmill or running pace box turns a speed into both. Pace in minutes is 60 divided by the speed, so 10 km/h is 6:00 per km and 9:39 per mile, and 6 mph is 10:00 per mile and 6:13 per km. It also gives the time for 1 mile, 5 km and 10 km at that pace.

Where the numbers come from

NIST SP 811, Appendix B.8 lists the international mile as 1,609.344 m, the nautical mile as 1,852 m, and the knot as one nautical mile per hour (0.5144444 m/s). It also gives 1 mile per hour as 1.609344 km/h. Checked 24 Oct 2026. The converter keeps these as exact fractions and rounds only the last digit shown.

Mistakes to avoid

Do not round 1.609344 to 1.5 or 2. At 70 mph, 1.5 gives 105 km/h and the true figure is 112.7. Do not mix mph with mpg, which is fuel use. And on a car dial that shows both units, the larger numbers are km/h.

Related pages: Kph to mph, Mph to knots, Km to miles and Unit converter.