Miles per hour.
mph to Knots Converter — mph to kn
Convert mph (mph) to Knots (kn) using the exact conversion factor (1 mph = 0.8689762419 knots). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
mph to Knots converter
Converter
Speed Converter
Convert road, aviation, marine, lab, and scientific speed units.
Context values
Some unit families need one extra value for a physically accurate result.
A knot is one nautical mile per hour.
Result = input x 0.44704 / 0.5144444444.
Speed uses meters per second as the base unit.
Reserved above the conversion cards and below the converter.
About Converting mph to Knots
mph and Knots both describe speed, and the conversion matters whenever a maritime or aviation speed (knots) needs to be compared against a road speed (mph). mph is typically associated with united States (road speed limits and vehicle speedometers), while Knots is typically associated with used internationally in maritime navigation and aviation.
Formula
knots = mph × 0.868976241901
This factor comes from each unit's defined relationship to the category's base unit: 1 mph equals 0.44704 base units, and 1 knots equals 0.514444444444 base units, so dividing one by the other gives the direct mph-to-knots factor of 0.868976241901.
Simple example
1 mph × 0.8689762419 = 0.8689762419 kn
1 mph = 0.8689762419 knots.
Real-world example
10 mph × 0.8689762419 = 8.689762419 kn
10 mph = 8.689762419 knots.
Conversion table
| mph (mph) | Knots (kn) |
|---|---|
| 1 mph | 0.8689762419 kn |
| 5 mph | 4.34488121 kn |
| 10 mph | 8.689762419 kn |
| 25 mph | 21.72440605 kn |
| 50 mph | 43.4488121 kn |
| 100 mph | 86.89762419 kn |
Reverse conversion: Knots to mph
0.8689762419 kn × 1.150779448 = 1 mph
0.8689762419 knots = 1 mph.
mph = knots × 1.15077944802
For a page dedicated to this direction, see Knots to mph.
mph vs. Knots
| Aspect | mph | Knots |
|---|---|---|
| Family | US/imperial customary unit | Non-SI unit accepted for use with SI (maritime/aviation) |
| Typical use | Road speed limits and vehicle speedometers in the US and UK | Ship and boat speed in marine navigation |
| Where it's used | United States (road speed limits and vehicle speedometers) | Used internationally in maritime navigation and aviation |
Understanding the mph
mph (mph) measures speed. Miles per hour follows directly from the international statute mile (1,609.344 m) divided by one hour. It is classified as a US/imperial customary unit.
Where it's used: United States (road speed limits and vehicle speedometers) United Kingdom (road speed limits)
Uses of the mph today
- Road speed limits and vehicle speedometers in the US and UK
- Weather reporting (wind speed) in the US
- Sports statistics (e.g. pitch speed, wind gusts) in US media
History of the mph
Miles per hour is a compound unit with no separate origin story of its own — it follows automatically once the statute mile was fixed at 5,280 feet in 1593 and later refined to exactly 1,609.344 meters by the 1959 international agreement that also standardized the pound.
Historical origin. mph was not the invention of a single named person; it developed through the process described above.
Understanding the Knots
Knots (kn) measures speed. A knot is one nautical mile per hour; since the nautical mile is exactly 1,852 meters, a knot is exactly 1,852/3,600 m/s. It is classified as a Non-SI unit accepted for use with SI (maritime/aviation).
Where it's used: Used internationally in maritime navigation and aviation
Uses of the Knots today
- Ship and boat speed in marine navigation
- Aircraft airspeed and wind speed reporting in aviation
- Marine weather forecasts (wind speed)
History of the Knots
The knot gets its name from an old nautical method of measuring speed: sailors trailed a 'log line' with evenly spaced knots behind a ship and counted how many knots paid out over a fixed time, giving a direct speed reading in 'knots.'
The nautical mile it's based on was itself standardized internationally in 1929 (the International Nautical Mile, 1,852 m exactly), tying the knot to a precise value still used in shipping and aviation today.
Historical origin. Knots was not the invention of a single named person; it developed through the process described above.
mph — sources
- NIST — International yard and pound (1959) — Basis for the modern mile used in mph.
Knots — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Lists the knot among accepted non-SI speed units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many knots are in 1 mph?
1 mph equals 0.8689762419 knots, using the exact defined conversion factor rather than an estimate.
How do I convert mph to knots?
Multiply the mph value by 0.8689762419. The converter above does this instantly to whatever precision you set.
How do I convert knots back to mph?
Use the reverse factor: 1 knots equals 1.150779448 mph. You can also use the swap control in the converter above to flip the direction instantly.
What is a mph?
mph (mph) measures speed. Miles per hour follows directly from the international statute mile (1,609.344 m) divided by one hour. It is classified as a US/imperial customary unit.
What is a knots?
Knots (kn) measures speed. A knot is one nautical mile per hour; since the nautical mile is exactly 1,852 meters, a knot is exactly 1,852/3,600 m/s. It is classified as a Non-SI unit accepted for use with SI (maritime/aviation).
Is the mph to knots conversion exact?
Yes. A knot is one nautical mile per hour; since the nautical mile is exactly 1,852 meters, a knot is exactly 1,852/3,600 m/s. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the mph still used today?
United States (road speed limits and vehicle speedometers) United Kingdom (road speed limits)