Written by Muneeb Rana · Last updated 26 October 2026
Quick answer: What is a knot? A knot is one nautical mile per hour, exactly 1.852 km/h or about 1.151 mph. Ships and aircraft use it because a nautical mile relates to one minute of latitude, which makes chart navigation easy. A boat at 20 knots is moving about 23 mph. Speedometer PRO displays mph and km/h, not knots.
TL;DR
- 1 knot = 1 nautical mile per hour.
- = 1.852 km/h exactly.
- ≈ 1.151 mph.
- Used at sea and in aviation.
- Convert with our tool.
What is a knot: definition
The international nautical mile is exactly 1,852 m, so one knot is 1.852 km/h. NIST and Wikipedia confirm the definition.
Why the name
Sailors once measured speed by letting out a line with knots tied at intervals and counting knots passing in a set time.
Conversion table
| knots | mph | km/h |
|---|---|---|
| 5 | 5.8 | 9.3 |
| 10 | 11.5 | 18.5 |
| 20 | 23.0 | 37.0 |
| 30 | 34.5 | 55.6 |
| 100 | 115.1 | 185.2 |
| 450 | 517.9 | 833.4 |
Knots on water and in the air
Boats measure speed over ground (GPS) or through water (log). Aircraft use knots for airspeed and ground speed; see airplane speed app.
Using a phone at sea
GPS gives speed over ground. Convert with knots to mph. Keep phones dry. See boat speedometer.
Why knots stuck
Sailors once measured speed by letting out a line knotted at regular intervals and counting the knots that ran out in a set time, using a log line. The unit survived because one nautical mile is about one minute of latitude, which makes chart navigation easy. A knot is now defined as exactly 1.852 km/h, about 1.151 mph.
Knots in aviation
Pilots and air traffic controllers use knots for airspeed and wind. A light aircraft might cruise around 100–120 knots, while airliners cruise at several hundred knots of true airspeed.
Converting in your head
Add about 15% to knots for mph (20 knots ≈ 23 mph), or roughly double knots and subtract 10% for km/h (20 knots ≈ 37 km/h).
Knots on land?
Knots are rarely used on land, but some boat and aviation speedometer apps offer them. Speedometer PRO shows MPH and KM/H only.
Origin of the word
Sailors once measured speed by letting out a line knotted at regular intervals behind the ship and counting how many knots ran out in a set time, using a sandglass. The name stuck.
App support
Speedometer PRO shows MPH and KM/H; knots are not offered.
Related: MPH guide: speed units explained · Knots to MPH converter · Boat speedometer app: GPS speed over ground · Airplane speed app: measuring ground speed · MPH vs km/h · What does mph mean? · Speedometer MPH and KM/H units · KMH to MPH converter
Get Speedometer PRO on Google Play · Download on the App Store · Set it up before you move; never handle your phone while driving.
Sources
- Knot (unit) (Wikipedia): en.wikipedia.org (accessed 26 October 2026)
- Unit conversion (NIST Office of Weights and Measures): nist.gov (accessed 26 October 2026)
FAQ
How fast is one knot?
Exactly 1.852 km/h, or about 1.151 mph.
Why do boats use knots?
A nautical mile matches one minute of latitude, which simplifies navigation on charts.
Is a knot faster than a mph?
Yes, one knot is about 15% faster than one mph.
Do planes use knots?
Yes, aviation uses knots for airspeed and ground speed.
Does Speedometer PRO show knots?
No. It shows MPH and KM/H. Use our knots converter.