A knot is one nautical mile per hour.
Knots to Speed of lights Converter — kn to c
Convert Knots (kn) to Speed of light (c) using the exact conversion factor (1 knots = 1.716002e-9 speed of light). See the formula, worked examples, conversion table, history, and common uses.
Knots to Speed of lights 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.
Speed of light in vacuum.
Result = input x 0.5144444444 / 2.99792458e+8.
Speed uses meters per second as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Knots to Speed of lights
Knots and Speed of light both describe speed, and the conversion matters whenever a maritime or aviation speed (knots) needs to be compared against a road speed (mph). Knots is most often used for ship and boat speed in marine navigation.
Formula
speed of lights = knots × 1.716002e-9
This factor comes from each unit's defined relationship to the category's base unit: 1 knots equals 0.514444444444 base units, and 1 speed of light equals 299792458 base units, so dividing one by the other gives the direct knots-to-speed of light factor of 1.716002e-9.
Simple example
1 kn × 1.716002e-9 = 1.716002e-9 c
1 knots = 1.716002e-9 speed of lights.
Real-world example
10 kn × 1.716002e-9 = 1.716002e-8 c
10 knots = 1.716002e-8 speed of lights.
Conversion table
| Knots (kn) | Speed of light (c) |
|---|---|
| 1 kn | 1.716002e-9 c |
| 5 kn | 8.58001e-9 c |
| 10 kn | 1.716002e-8 c |
| 25 kn | 4.290005e-8 c |
| 50 kn | 8.58001e-8 c |
| 100 kn | 1.716002e-7 c |
Reverse conversion: Speed of light to Knots
1.716002e-9 c × 582749918.4 = 1.000000025 kn
1.716002e-9 speed of lights = 1.000000025 knots.
knots = speed of lights × 582749918.359
For a page dedicated to this direction, see Speed of light to Knots.
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.
Understanding the Speed of light (c)
Speed of light in vacuum.
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 speed of lights are in 1 knots?
1 knots equals 1.716002e-9 speed of lights, using the exact defined conversion factor rather than an estimate.
How do I convert knots to speed of light?
Multiply the knots value by 1.716002e-9. The converter above does this instantly to whatever precision you set.
How do I convert speed of light back to knots?
Use the reverse factor: 1 speed of light equals 582,749,918.4 knots. You can also use the swap control in the converter above to flip the direction instantly.
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).
What is a speed of light?
Speed of light (c) is a unit of speed.
Is the knots to speed of light 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 knots still used today?
Used internationally in maritime navigation and aviation