Mach to km/h Converter
Convert Mach number to kilometres per hour — at sea level Mach 1 is about 1,225 km/h. Results update as you type; exact factors shown.
One Mach (sea level, 15 °C) is 1,225.044 kilometres per hour — see the exact factor, not a rounded rule of thumb.
How the mach to km/h 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.
The UK is metric for most trade and science but keeps miles, pints, stone and mpg (with the imperial gallon) in daily life.
Common speed conversions
| From | To | Units |
|---|---|---|
| 0.5 Ma | 612.522 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 0.8 Ma | 980.0352 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 0.85 Ma | 1,041.2874 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 0.9 Ma | 1,102.5396 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 1 Ma | 1,225.044 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 1.5 Ma | 1,837.566 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 2 Ma | 2,450.088 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 2.5 Ma | 3,062.61 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 3 Ma | 3,675.132 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 5 Ma | 6,125.22 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 8 Ma | 9,800.352 km/h | Mach (sea level, 15 °C) to kilometres per hour |
| 10 Ma | 12,250.44 km/h | Mach (sea level, 15 °C) to kilometres 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 Mach 1 in km/h?
About 1,225 km/h at sea level in standard conditions.
Does Mach 1 change with altitude?
Yes. The speed of sound falls with temperature, so Mach 1 at cruising altitude is nearer 1,060 km/h. This page uses the sea-level value.
What is a typical airliner cruise speed?
About Mach 0.85, roughly 900 km/h at altitude.
What is Mach 2?
Twice the speed of sound — Concorde cruised at about Mach 2.02.
What is hypersonic?
Mach 5 and above.
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 Physical Laboratory (NPL) — United Kingdom's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.