MPH to Knots Converter
Convert miles per hour to knots — a knot is 1.151 mph. Results update as you type; exact factors shown.
One mile per hour is 0.869 knots — see the exact factor, not a rounded rule of thumb.
How the mph to knots 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 |
|---|---|---|
| 1 mph | 0.869 kn | mile per hour to knots |
| 5 mph | 4.3449 kn | miles per hour to knots |
| 10 mph | 8.6898 kn | miles per hour to knots |
| 15 mph | 13.0346 kn | miles per hour to knots |
| 20 mph | 17.3795 kn | miles per hour to knots |
| 25 mph | 21.7244 kn | miles per hour to knots |
| 30 mph | 26.0693 kn | miles per hour to knots |
| 40 mph | 34.759 kn | miles per hour to knots |
| 50 mph | 43.4488 kn | miles per hour to knots |
| 60 mph | 52.1386 kn | miles per hour to knots |
| 100 mph | 86.8976 kn | miles per hour to knots |
| 200 mph | 173.7952 kn | miles per hour to knots |
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 a knot?
One nautical mile per hour — 1.852 km/h, or 1.151 mph.
Why do boats and planes use knots?
Because a nautical mile is one minute of latitude, so speed and position arithmetic line up on a chart.
What is 30 mph in knots?
26.1 knots.
Is a knot faster than a mph?
Yes, by about 15%.
Do you say "knots per hour"?
No — a knot already is a speed. "Knots per hour" would be an acceleration.
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.