Convert Mile per hour to Kilometre per hour

Quick answer: Mile per hour to Kilometre per hour

1 Mile per hour = 1.609344 Kilometre per hour (mph → km/h). To convert mile per hour to kilometre per hour, multiply by 1.609344. To convert kilometre per hour to mile per hour, multiply by 0.6213712. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common mile per hour-to-kilometre per hour questions.

How to convert Mile per hour to Kilometre per hour

To convert mile per hour to kilometre per hour, multiply the number of mile per hour by the conversion factor 1.609344, because 1 mph = 1.609344 km/h. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 km/h = 0.6213712 mph, so you divide by 1.609344 (or multiply by 0.6213712) to turn kilometre per hour back into mile per hour.

km/h = mph × 1.609344  ·  mph = km/h × 0.6213712

1. Write down the value you want to convert, in mile per hour.
2. Multiply it by 1.609344.
3. The result is the same area/length/quantity expressed in kilometre per hour.

Mile per hour to Kilometre per hour — worked examples

Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 mile per hour is 8.04672 kilometre per hour because 5 mph × 1.609344 = 8.04672 km/h.

Common Mile per hour to Kilometre per hour conversions

These are the mile per hour-to-kilometre per hour values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:

• 1 mile per hour = 1.609344 kilometre per hour
• 2 mile per hour = 3.218688 kilometre per hour
• 2.5 mile per hour = 4.02336 kilometre per hour
• 3 mile per hour = 4.828032 kilometre per hour
• 4 mile per hour = 6.437376 kilometre per hour
• 5 mile per hour = 8.04672 kilometre per hour
• 6 mile per hour = 9.656064 kilometre per hour
• 7 mile per hour = 11.26541 kilometre per hour
• 8 mile per hour = 12.87475 kilometre per hour
• 9 mile per hour = 14.4841 kilometre per hour
• 10 mile per hour = 16.09344 kilometre per hour
• 12 mile per hour = 19.31213 kilometre per hour
• 15 mile per hour = 24.14016 kilometre per hour
• 20 mile per hour = 32.18688 kilometre per hour
• 25 mile per hour = 40.2336 kilometre per hour
• 30 mile per hour = 48.28032 kilometre per hour
• 50 mile per hour = 80.4672 kilometre per hour
• 75 mile per hour = 120.7008 kilometre per hour
• 100 mile per hour = 160.9344 kilometre per hour
• 200 mile per hour = 321.8688 kilometre per hour
• 500 mile per hour = 804.672 kilometre per hour
• 1000 mile per hour = 1,609.344 kilometre per hour

Mile per hour to Kilometre per hour conversion chart (both directions)

The chart below converts mile per hour to kilometre per hour and kilometre per hour to mile per hour side by side, so it works whichever way you need. 1 mile per hour = 1.609344 kilometre per hour, and 1 kilometre per hour = 0.6213712 mile per hour.

Mile per hour vs Kilometre per hour: which is bigger?

A mile per hour is the larger unit: one mile per hour equals 1.609344 kilometre per hours. Put another way, you need 1.609344 kilometre per hours to make a single mile per hour.

What is a Mile per hour? History, origin and usage

The mile per hour expresses speed in imperial miles travelled each hour and is one of the oldest everyday speed units in the English-speaking world. It survives from the British imperial and US customary systems even where metric units rule elsewhere.

Miles per hour is the unit on road signs, speed limits and car speedometers in the United States, the United Kingdom and a handful of related territories. It is also common for reporting wind and storm speeds in those countries.

One mile per hour equals exactly 1.609344 kilometres per hour — the same exact factor that relates the mile to the kilometre. Although mph rules the road in the US and UK, both countries switch to knots at sea and in the air.

What is a Kilometre per hour? History, origin and usage

The kilometre per hour pairs the metric kilometre with the hour, and it became the everyday road-speed unit as the metric system spread worldwide. It is a non-coherent metric unit — it mixes the kilometre with the hour rather than the second — but its human scale made it the popular choice for travel.

Kilometres per hour is the speed unit on road signs and vehicle speedometers across most of the world, the metric standard for traffic and travel. Many countries’ weather services also report wind speeds in km/h.

One kilometre per hour is exactly five-eighteenths of a metre per second, because an hour is 3,600 seconds and a kilometre is 1,000 metres. Most of the world posts road-sign speed limits in km/h, with the United States and United Kingdom among the few using miles per hour.

Convert 1 Mile per hour to other units

It can help to see a mile per hour next to the other units it is commonly compared with. One mile per hour (mph) is equal to:

Convert 1 Kilometre per hour to other units

One kilometre per hour (km/h) is equal to:

Tips for converting Mile per hour to Kilometre per hour

• To go from mile per hour to kilometre per hour, multiply by 1.609344; to go back, divide by 1.609344 (or multiply by 0.6213712).
• For a quick mental estimate, remember that 1 mile per hour ≈ 1.609344 kilometre per hour, so 10 mile per hour ≈ 16.09344 kilometre per hour.
• The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
• Both fields update live as you type — change either side to convert in that direction.

How to use this Mile per hour to Kilometre per hour converter

Type a number into the Mile per hour field and the equivalent in Kilometre per hour appears instantly — there is no “convert” button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Kilometre per hour field to convert the other way (kilometre per hour to mile per hour). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above — use the chart for quick look-ups and the tool for precise work.

Accuracy and method

Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 mph = 1.609344 km/h), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for mile per hour-to-kilometre per hour conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.

Sources

• NIST Special Publication 811 — Guide for the Use of the SI — publishes the exact metric equivalents of the customary units. The inch, foot, yard and mile are defined exactly in metres by the 1959 international yard-and-pound agreement, so every imperial figure on this page is exact, not rounded.
• BIPM — The International System of Units (SI Brochure) — the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.

All speed factors are exact: 1 m/s = 3.6 km/h, 1 mph = 1.609344 km/h, 1 knot = 1.852 km/h, 1 ft/s = 0.3048 m/s. So the live tool and every number on this page always agree.

Frequently asked questions

How many kilometre per hour are in 1 mile per hour?

1 mile per hour = 1.609344 kilometre per hour (km/h). To convert any number of mile per hour to kilometre per hour, multiply by 1.609344.

How do I convert mile per hour to kilometre per hour?

Multiply the number of mile per hour by 1.609344. For example, 10 mile per hour = 10 × 1.609344 = 16.09344 kilometre per hour, and 25 mile per hour = 40.2336 kilometre per hour.

How many mile per hour are in 1 kilometre per hour?

1 kilometre per hour = 0.6213712 mile per hour. So to convert kilometre per hour back to mile per hour, multiply by 0.6213712.

What is the formula to convert mile per hour to kilometre per hour?

kilometre per hour = mile per hour × 1.609344. The reverse formula is mile per hour = kilometre per hour × 0.6213712.

How much is 100 mile per hour in kilometre per hour?

100 mile per hour = 160.9344 kilometre per hour. (And 1000 mile per hour = 1,609.344 kilometre per hour.)

Which is bigger, a mile per hour or a kilometre per hour?

A mile per hour is larger: 1 mile per hour = 1.609344 kilometre per hour.

Is this mile per hour to kilometre per hour converter accurate?

Yes — every value is computed from the exact 1.609344 km/h per mph factor (not rounded look-up tables), and the factors are re-verified automatically on every update.

Can I convert kilometre per hour to mile per hour too?

Yes. The converter works both ways — enter a value in either field. 1 kilometre per hour = 0.6213712 mile per hour.

Related speed conversions

• Kilometre per hour to Mile per hour
• Kilometre per hour to Millimetre per second
• Centimetre per second to Kilometre per hour
• Foot per second to Kilometre per hour
• Millimetre per second to Kilometre per hour
• Kilometre per hour to Centimetre per second
• Kilometre per hour to Foot per second
• Kilometre per hour to Metre per second
• Metre per second to Kilometre per hour
• Metre per second to Mile per hour

See all speed conversions →