# Knots to MPH Speed Converter

Convert knots to mph, km/h, and m/s. Free nautical speed converter for sailing, aviation, and meteorology. Based on exact international nautical mile.

## What this calculates

Convert between knots, miles per hour, kilometers per hour, and meters per second. Knots are the standard speed unit in maritime navigation, aviation, and meteorology, defined as one nautical mile per hour.

## Inputs

- **Speed Value** — min 0 — Enter the speed to convert.
- **From Unit** — options: Knots (kn), Miles per Hour (mph), Kilometers per Hour (km/h), Meters per Second (m/s) — Select the source speed unit.

## Outputs

- **Knots** (kn) — Speed in knots (nautical miles per hour).
- **Miles per Hour** (mph) — Speed in statute miles per hour.
- **Kilometers per Hour** (km/h) — Speed in kilometers per hour.
- **Meters per Second** (m/s) — Speed in meters per second.

## Details

A knot is one nautical mile per hour. The international nautical mile is defined as exactly 1,852 meters, making the knot a precisely defined unit. This converter uses that exact definition for all calculations.

Exact conversion factors

- 1 knot = 1.852 km/h (exact, from the nautical mile definition)

- 1 knot = 1.15078 mph (derived from 1852 ÷ 1609.344)

- 1 knot = 0.514444 m/s (derived from 1852 ÷ 3600)

- 1 mph = 0.868976 knots

Speed Reference Table

Knots
MPH
km/h
m/s
Context

5
5.75
9.26
2.57
Light breeze sailing

15
17.26
27.78
7.72
Moderate sailing speed

30
34.52
55.56
15.43
Fast motorboat

64
73.65
118.53
32.92
Hurricane threshold

250
287.69
463.00
128.61
Commercial aircraft approach

480
552.37
889.00
247.00
Cruising airliner

The term "knot" comes from the historical practice of measuring ship speed by counting knots on a rope as they passed over the stern. The knots were spaced at regular intervals, and a sandglass timed the measurement.

## Frequently Asked Questions

**Q: Why do ships and planes use knots instead of mph?**

A: Knots are based on the nautical mile, which equals one minute of latitude on the Earth. This makes nautical miles directly useful for navigation on charts and maps. Since maritime and aviation navigation rely heavily on latitude and longitude, knots provide a natural and practical speed unit.

**Q: How fast is 1 knot in mph?**

A: One knot equals approximately 1.15078 miles per hour (mph). This is derived from the exact definitions: 1 nautical mile = 1,852 meters and 1 statute mile = 1,609.344 meters.

**Q: What wind speed is a hurricane?**

A: A tropical cyclone is classified as a hurricane (or typhoon) when sustained wind speeds reach 64 knots (74 mph, 119 km/h) or higher. The Saffir-Simpson scale then categorizes hurricanes from Category 1 (64-82 knots) to Category 5 (137+ knots).

**Q: What is a nautical mile?**

A: A nautical mile is defined as exactly 1,852 meters (about 1.151 statute miles or 6,076 feet). Historically, it was defined as one minute of arc of latitude along any meridian, making it extremely practical for marine and air navigation.

---

Source: https://vastcalc.com/calculators/everyday/knots-to-mph
Category: Everyday Life
Last updated: 2026-04-21