Unit converter
Speed converter
Instant conversion in your browser — speed.
≈ 0.6214 mph
Tip: enter the values one by one — 40 30 55 20 — and you get the total and the average.
1 km/h = 0.6213711923 mph
Quick table Kilometers per hour → Miles per hour
| km/h | mph |
|---|---|
| 1 | 0.6213711923 |
| 5 | 3.106855961 |
| 10 | 6.213711923 |
| 25 | 15.53427981 |
| 50 | 31.06855961 |
| 100 | 62.13711923 |
| 500 | 310.6855961 |
| 1,000 | 621.3711923 |
All unit families
- Lengthmm · cm · m · km · in · ft · yd · miAlmost the whole world measures length in metres. The exceptions are narrow but stubborn: the United States uses feet and inches for everyday distances, and the United Kingdom still posts road signs in miles while selling timber in millimetres.
- Weight / Massmg · g · kg · t · oz · lb · stThe kilogram is the base unit, and until 2019 it was the last one still defined by a physical object: a platinum-iridium cylinder kept near Paris. It is now defined through the Planck constant, so it can be reproduced in any properly equipped laboratory.
- Temperature°C · °F · KTemperature is the one family here that is not a multiplication. Celsius and Fahrenheit have different zero points as well as different step sizes, so you need the formula: °F = °C × 9/5 + 32.
- Volumeml · l · m³ · gal · pt · fl oz · cupThis is the family where the same word means two different amounts. American and British measures share their names but not their sizes, and a recipe that ignores the difference will not work.
- Aream² · km² · ha · ft² · acAreas are where a linear conversion quietly goes wrong. One metre is 3.28 feet, but one square metre is 10.76 square feet — the factor is squared. Converting the sides and forgetting the square is the single most common mistake in this family.
- Times · min · h · d · wk · mo · yrSeconds, minutes, hours, days and weeks convert exactly. Months and years do not, and no converter can make them.
- Digital storagebit · B · KB · MB · GB · TBDigital storage has two conflicting definitions of the same prefixes, and almost every confusion about file sizes comes from that.
1 kilometers per hour (km/h) in every unit
| Miles per hour | 0.6213711923 mph |
| Meters per second | 0.2777777778 m/s |
| Knots | 0.5399568035 kn |
About speed units
Four units, four different worlds. Kilometres per hour on European roads, miles per hour in the US and UK, metres per second in physics and weather bulletins, knots at sea and in the air.
The knot is the interesting one: it is one nautical mile per hour, and a nautical mile is one minute of latitude. That is why sailors can measure distance on a chart with dividers against the latitude scale in the margin — no conversion needed. "Knots per hour" is wrong; a knot is already a speed.
The one rule worth memorising: metres per second × 3.6 = kilometres per hour.
About this conversion
Speed conversion: 1 kilometers per hour (km/h) equals 0.6213711923 mph. As a practical reference, 2 km/h = 1.242742385 mph — relevant for driving, running pace and wind forecasts.
| km/h | mph |
|---|---|
| 2 | 1.242742385 |
Frequently asked questions
Why is wind speed given in metres per second?
Because it is the SI unit, and many national weather services publish in it. To read it as road speed, multiply by 3.6: a 10 m/s wind is 36 km/h.
What speed limits will I meet abroad?
Typical European limits are 50 km/h in town (31 mph), 90 km/h on main roads (56 mph) and 130 km/h on motorways (81 mph). British motorways are 70 mph (113 km/h), US interstates commonly 65–75 mph (105–121 km/h).
How fast is a boat in knots, really?
A cruising sailboat does 5–8 knots (9–15 km/h), a motorboat 25–30 knots (46–56 km/h), an airliner cruises around 450–500 knots (830–930 km/h).
Can I estimate mph from km/h in my head?
Take away a third and you are within a couple of per cent: 100 km/h minus a third is about 66, the true value is 62 mph. Good enough to read a road sign, not to argue with a speed camera.