KPH to MPH Converter

Common questions

How many mph is 100 km/h?

62.1371192237 mph as this page prints it, or 62.14 mph rounded. Every kilometre per hour is 0.621371192237 mph, so multiply by that figure or divide by 1.609344: 10 km/h is 6.21371192237 mph, 50 km/h is 31.0685596119 mph, 80 km/h is 49.709695379 mph, 130 km/h is 80.7782549909 mph and 200 km/h is 124.274238447 mph.

What is the formula for kph to mph?

mph = km/h / 1.609344, and km/h = mph × 1.609344 in the other direction. The international mile is defined as exactly 1,609.344 metres and an hour is exactly 3,600 seconds, so the factor is a definition rather than a measurement. Reduced, the kph to mph ratio is the exact fraction 15625/25146. The converter carries the speed through metres per second using those defined figures rather than a rounded 0.62, which is why 100 km/h comes back as 62.1371192237 mph and not 62.

How do I convert km/h to mph in my head?

Multiply by five and divide by eight, which is 0.625 against the true 0.621371192237. So 80 km/h is 80 × 5 / 8 = 50 mph against the exact 49.709695379, and 120 km/h is 75 mph against 74.5645430685. The shortcut runs 0.584 percent high, which is 0.36 mph too much at 100 km/h and 0.44 mph too much at 120 km/h. The Fibonacci pairs are closer still and easier to recall: 8 km/h is 4.9709695379 mph, 13 km/h is 8.07782549909 mph and 21 km/h is 13.048795037 mph.

What are the common speed limits in km/h in mph?

30 km/h is 18.64 mph, 50 km/h is 31.07 mph, 60 km/h is 37.28 mph, 70 km/h is 43.5 mph, 80 km/h is 49.71 mph, 90 km/h is 55.92 mph, 100 km/h is 62.14 mph, 110 km/h is 68.35 mph, 120 km/h is 74.56 mph and 130 km/h is 80.78 mph. Those are rounded to two decimals here; the chart under the converter has the same list, and typing the number in the From box gives it to twelve significant digits.

Is kph the same as km/h?

Yes. kph, kmph, km/hr and KMH are all informal ways of writing kilometres per hour, and km/h is the form used on road signs and in SI, where the solidus means per. This page uses the two interchangeably: the From menu lists the unit as Kilometre per hour (km/h), and the heading above the list reads 100 km/h in every speed unit when you type 100.

Is the kph to mph conversion exact?

The factor is exact, the decimal is not. A mile is defined as exactly 1,609.344 metres, so nothing is measured or estimated here. Going from miles per hour to kilometres per hour the arithmetic even terminates, because multiplying by 1.609344 is a finite decimal: 30 mph is exactly 48.28032 km/h, 60 mph is exactly 96.56064 km/h and 70 mph is exactly 112.65408 km/h. The other direction divides by that number, and since 25146 is 2 × 3 × 3 × 11 × 127 the result repeats forever, so this page shows twelve significant digits, comfortably inside what double-precision arithmetic holds.

Can I convert mph back to km/h on this page?

Yes. The swap button between the two boxes reverses the pair, so the page becomes an mph to km/h converter without a reload: 1 mph is 1.609344 km/h, 55 mph is 88.51392 km/h, 65 mph is 104.60736 km/h and 75 mph is 120.7008 km/h, all exact. Both unit menus stay open as well, so the same figure will go to metres per second, feet per second or knots without leaving the page, and Copy result copies the headline exactly as printed, without the thousands separators.

How do I get m/s or knots at the same time?

The list under the answer already has them, because the converter works out every speed unit at once instead of making you pick one target. Kilometres per hour divided by 3.6 gives metres per second and divided by 1.852 gives knots, both exact definitions, so 100 km/h reads as 62.1371192237 mph, 27.7777777778 m/s, 91.1344415281 ft/s and 53.9956803456 kn together. Each row has its own Copy button.

Will this tell me what my speedometer should read?

No, it converts the number you give it and nothing more. Vehicle rules in the UK and the EU allow a speedometer to read high but never low, so a car showing 100 km/h is often doing a little less, and a change of tyre or wheel size shifts the reading again. Convert the true speed you are working from, and use the tyre size calculator linked below if you have changed wheels.

Why does the page open on km/h and mph when I last converted something else?

Because a page that names a pair should show that pair. This one sets kilometres per hour and miles per hour on arrival, ahead of whatever the converter last remembered, and it leaves the main unit converter's own pair alone: go back there and it is still on the units you left it on. The number you last typed does travel with you, since it is usually the one you are still working on.

Is anything I type sent anywhere?

No. The conversion is arithmetic against a table of factors that ships with the page, so it runs in your browser with nothing uploaded and no account, and it keeps working with no network connection once the page has loaded.