KM/H to MPH Converter
Convert kilometres per hour to miles per hour — multiply by 0.6214. Results update as you type; exact factors shown.
One kilometre per hour is 0.6214 miles per hour — see the exact factor, not a rounded rule of thumb.
How the km/h to mph converter works
Speeds convert through metres per second. 1 km/h is 1000/3600 m/s; 1 mph is 1609.344/3600 m/s; a knot is one nautical mile (1,852 m) per hour. Mach is shown against the standard sea-level speed of sound of 340.29 m/s and varies with altitude and temperature.
Australia is fully metric under the National Measurement Act 1960; imperial units appear only in trade with the US and in older documents.
Common speed conversions
| From | To | Units |
|---|---|---|
| 10 km/h | 6.2137 mph | kilometres per hour to miles per hour |
| 20 km/h | 12.4274 mph | kilometres per hour to miles per hour |
| 30 km/h | 18.6411 mph | kilometres per hour to miles per hour |
| 40 km/h | 24.8548 mph | kilometres per hour to miles per hour |
| 50 km/h | 31.0686 mph | kilometres per hour to miles per hour |
| 60 km/h | 37.2823 mph | kilometres per hour to miles per hour |
| 80 km/h | 49.7097 mph | kilometres per hour to miles per hour |
| 90 km/h | 55.9234 mph | kilometres per hour to miles per hour |
| 100 km/h | 62.1371 mph | kilometres per hour to miles per hour |
| 110 km/h | 68.3508 mph | kilometres per hour to miles per hour |
| 120 km/h | 74.5645 mph | kilometres per hour to miles per hour |
| 130 km/h | 80.7783 mph | kilometres per hour to miles per hour |
Units in this converter and their exact factors
| Unit | Symbol | One unit in metre per seconds |
|---|---|---|
| metre per second | m/s | 1 metre per second |
| kilometre per hour | km/h | 0.2777777778 metre per second |
| mile per hour | mph | 0.44704 metre per second |
| knot | kn | 0.5144444444 metre per second |
| foot per second | ft/s | 0.3048 metre per second |
| Mach (sea level, 15 °C) | Ma | 340.29 metre per second |
FAQFrequently asked questions about speed conversion
What is 100 km/h in mph?
62.1 mph.
What is a 50 km/h urban limit in mph?
31 mph, which is why UK towns post 30.
How do I estimate km/h to mph?
Take six-tenths: 80 km/h is about 48 mph, and exactly 49.7.
What is the fastest common speed limit?
130 km/h in much of Europe, which is 80.8 mph.
Does this work for wind speed?
Yes — the conversion is the same for any speed. Knots need the knots page.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Measurement Institute (NMI) — Australia's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.