MPH to Mach Converter
Convert miles per hour to Mach number at sea level and 15 °C. Results update as you type; exact factors shown.
One mile per hour is 0.0013 Mach (sea level, 15 °C) — see the exact factor, not a rounded rule of thumb.
How the mph to mach 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 |
|---|---|---|
| 100 mph | 0.1314 Ma | miles per hour to Mach (sea level, 15 °C) |
| 250 mph | 0.3284 Ma | miles per hour to Mach (sea level, 15 °C) |
| 500 mph | 0.6569 Ma | miles per hour to Mach (sea level, 15 °C) |
| 600 mph | 0.7882 Ma | miles per hour to Mach (sea level, 15 °C) |
| 700 mph | 0.9196 Ma | miles per hour to Mach (sea level, 15 °C) |
| 761 mph | 0.9997 Ma | miles per hour to Mach (sea level, 15 °C) |
| 800 mph | 1.051 Ma | miles per hour to Mach (sea level, 15 °C) |
| 1,000 mph | 1.3137 Ma | miles per hour to Mach (sea level, 15 °C) |
| 1,200 mph | 1.5764 Ma | miles per hour to Mach (sea level, 15 °C) |
| 1,522 mph | 1.9995 Ma | miles per hour to Mach (sea level, 15 °C) |
| 2,000 mph | 2.6274 Ma | miles per hour to Mach (sea level, 15 °C) |
| 3,000 mph | 3.9411 Ma | miles per hour to Mach (sea level, 15 °C) |
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 speed is Mach 1?
761 mph at sea level, 15 °C.
Why the temperature qualifier?
The speed of sound tracks air temperature, not pressure, so the same Mach number is a different ground speed at altitude.
What is 600 mph in Mach?
About Mach 0.79 at sea level.
What is the fastest crewed aircraft?
The X-15 reached Mach 6.7, about 4,520 mph.
Is Mach a fixed speed?
No — it is a ratio to the local speed of sound, which is why it is used in aviation at all.
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.