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 meters 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 US uses customary units (US gallon, short ton, °F) in daily life; NIST SP 811 gives the exact SI factors.
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 meter per seconds |
|---|---|---|
| meter per second | m/s | 1 meter per second |
| kilometer per hour | km/h | 0.2777777778 meter per second |
| mile per hour | mph | 0.44704 meter per second |
| knot | kn | 0.5144444444 meter per second |
| foot per second | ft/s | 0.3048 meter per second |
| Mach (sea level, 15 °C) | Ma | 340.29 meter 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 Institute of Standards and Technology (NIST) — United States's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.