# Knots to miles per hour converter

> Convert knots to miles per hour (knots to mph) with the exact factor, a conversion chart and worked steps.

Interactive version: https://www.calcopenly.com/conversion/knots-to-mph
Subject: Unit converters

Knots describe nautical miles per hour and are used for marine and aviation speeds. They are a speed unit already, so knots per hour would mean a change in speed. Wind and current can also make speed through water differ from speed over ground.

One knot is about 1.150779448 miles per hour, so 20 kn is 23.015589 mph. To convert knots to mph, multiply by 1.150779448; to convert back, multiply by 0.8689762419.

One knot is one nautical mile (exactly 1,852 m) per hour. The factor has no exact decimal form, so results are computed with 50 significant digits and rounded only for display.

## Inputs

- **Knots (kn)**

## Results

- Miles per hour (mph) — main result
- Conversion
- 1 mph in knots (kn)

## Formula

$$
\text{miles per hour} = \text{knots} \times 1.15077944802
$$

## Worked examples

### 20 kn to mph

- Knots (kn): 20 kn
- **Miles per hour: 23.0155889605 mph**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 15 kn to mph

- Knots (kn): 15 kn
- **Miles per hour: 17.2616917204 mph**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

### 50 kn to mph

- Knots (kn): 50 kn
- **Miles per hour: 57.5389724012 mph**
- Checked against: Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions)

## Questions

### When would I convert knots to mph?

Knots describe nautical miles per hour and are used for marine and aviation speeds. They are a speed unit already, so knots per hour would mean a change in speed. Wind and current can also make speed through water differ from speed over ground.

### How many miles per hour are in a knot?

One knot is about 1.150779448 miles per hour. One knot is one nautical mile (exactly 1,852 m) per hour.

### How do you convert knots to mph?

Multiply the number of knots by 1.150779448. For example, 20 kn × 1.150779448 = 23.015589 mph. To go the other way, divide by 1.150779448.

### How can I estimate knots to mph without a calculator?

Multiply by 1.15. That is 0.06773% low of the exact factor 1.150779448, so 20 kn comes out as 23 mph instead of 23.0156.

### How accurate is the knots to miles per hour converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 3 worked examples whose answers come from independent sources; for example, “20 kn to mph” is checked against Exact-fraction computation from the legal unit definitions (scripts/gen-pairs.py, Python fractions).

### Where does the method come from?

NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B; NIST Handbook 44, Appendix C: General tables of units of measurement; BIPM, The International System of Units (SI Brochure), 9th edition.

## Sources

- [NIST SP 811 (2008), Guide for the Use of the International System of Units, Appendix B](https://www.nist.gov/pml/special-publication-811)
- [NIST Handbook 44, Appendix C: General tables of units of measurement](https://www.nist.gov/pml/weights-and-measures/publications/nist-handbooks/handbook-44)
- [BIPM, The International System of Units (SI Brochure), 9th edition](https://www.bipm.org/en/publications/si-brochure)