Convert between kilometres per hour, miles per hour, metres per second, and knots. All four units update live as you type in any field.
Type in any field — all four units update simultaneously.
| Reference | km/h | mph | kn |
|---|---|---|---|
| School zone (AU) | 40 | 24.9 | 21.6 |
| City speed limit (AU) | 50 | 31.1 | 27.0 |
| US highway limit | 105 | 65 | 56.7 |
| AU freeway limit | 110 | 68.4 | 59.4 |
| Gale-force wind | 75 | 46.6 | 40.5 |
| Cruising aircraft | 900 | 559 | 486 |
| Speed of sound (air) | 1235 | 767 | 667 |
Speed is expressed in different units depending on the context. Road speeds use km/h in Australia and most of the world, or mph in the United States and United Kingdom. Aviation and marine navigation use knots. Physics and engineering use metres per second. This converter handles all four simultaneously — change any value and the other three update instantly, making cross-context comparisons effortless.
Driving in the US or UK: Australians driving in the United States or United Kingdom encounter speed limits in mph. The most common limits — 25, 35, 55, and 65 mph — convert to approximately 40, 56, 88, and 105 km/h respectively. Knowing these pairs by heart (or checking this converter before your trip) makes it much easier to stay legal on unfamiliar roads.
Aviation & marine: Aircraft speeds and altitudes, as well as boat speeds and nautical distances, are measured in knots — a unit equal to one nautical mile per hour (1.852 km/h). A cruising speed of 450 knots is approximately 833 km/h. Marine weather forecasts also describe wind speed in knots, so converting to km/h helps you judge conditions quickly.
Sports & athletics: Sprint speeds in athletics and cycling are often reported in metres per second (m/s) for scientific analysis, while race speeds for cycling and motorsport are reported in km/h. Usain Bolt's 100 m world record of 9.58 seconds works out to approximately 10.44 m/s, or 37.6 km/h at peak velocity.
Weather reports: Wind speed is reported differently across platforms — the Bureau of Meteorology uses km/h, international weather services often use knots, and some datasets use m/s. This converter lets you cross-reference readings from different sources accurately.
A knot is one nautical mile per hour, where a nautical mile equals 1,852 metres (about 1.15 land miles). It is used in aviation and maritime navigation because nautical miles correspond directly to degrees of latitude on the earth's surface, making chart navigation much simpler. One knot equals approximately 1.852 km/h or 1.151 mph.
A close approximation is to multiply mph by 1.6 (the precise factor is 1.60934). So 60 mph ≈ 96.6 km/h, and 100 mph ≈ 160.9 km/h. For quick mental maths, multiply by 8 then divide by 5.
Convert between kilometres per hour, miles per hour, metres per second, and knots. All four units update live as you type in any field. MyCalcTools calculators are designed for quick everyday estimates with clear inputs, instant results and no account required. Results are provided for general information and planning, not as professional financial, medical, legal or trade advice.