Knots to Mph Converter

Quick Answer

Last updated: 11 November 2026 ·How we calculate this: NIST knot and nautical mile definitions

How This Knots to Mph Converter Works

Boats, ships, aircraft and marine weather forecasts give speed in knots, while cars and most people think in miles per hour or kilometers per hour. Choose the direction, enter the speed and press Calculate. The converter gives miles per hour to three decimal places (or knots), plus km/h, meters per second and feet per second.

How to Use the Knots to Mph Converter

1. Choose knots to mph or mph to knots.
2. Enter the speed.
3. Press Calculate.
4. Read the converted speed, plus km/h, m/s and ft/s.

Knots to Mph Formulas

• Knot: 1 kn = 1 nautical mile per hour = 1,852 m/h exactly
• mph from knots: mph = kn × 1,852 ÷ 1,609.344 = kn × 1.150779
• Knots from mph: kn = mph ÷ 1.150779 = mph × 0.868976
• km/h from knots: km/h = kn × 1.852
• Distance: 1 nautical mile = 1,852 m = 1.15078 statute miles

Key Terms

• Knot (kn, kt): one nautical mile per hour.
• Nautical mile (nmi): 1,852 m, about one minute of latitude.
• mph: statute miles per hour.
• km/h: kilometers per hour.
• Ground speed: speed over the ground, affected by wind or current.

Worked Example

A sailboat is making 7.5 knots. How fast is that in mph and km/h?

• 7.5 × 1.15078 = 8.63 mph
• 7.5 × 1.852 = 13.89 km/h
• Over 24 hours it would cover 180 nautical miles, or 207 statute miles.

Going the other way, a 35 mph gust is 35 ÷ 1.15078 = 30.4 knots.

Real-Life Examples

• Boating: a 25 kn speedboat is doing 28.8 mph.
• Aviation: a 120 kn approach speed is 138 mph.
• Weather: 64 kn hurricane-force wind is 73.6 mph.
• Cruise ships: 20 kn is 37.0 km/h.

Nautical Mile vs Statute Mile

• Nautical mile: 1,852 m, used at sea and in the air.
• Statute mile: 1,609.344 m, used on roads.
• Ratio: 1 nautical mile = 1.15078 miles.

Knots to Mph Chart

1 kn = 1.15078 mph = 1.852 km/h.

Why Sailors and Pilots Use Knots

The nautical mile was defined from the size of the Earth: one minute of latitude, one sixtieth of a degree, is about one nautical mile. That makes navigation on charts easy, because distance can be read straight off the latitude scale. Since 1929 the international nautical mile has been fixed at exactly 1,852 meters, and a knot is one nautical mile per hour. The name comes from the old practice of counting knots on a log line paid out behind a ship.

Marine forecasts, aviation weather and air traffic control all use knots, so wind warnings are given in knots too. A gale starts at 34 knots (39 mph) and hurricane-force wind at 64 knots (74 mph). When you see a wind speed or boat speed in knots, add about 15% to get mph. Do not confuse nautical miles with statute miles on a car odometer, which are about 13% shorter.

Keep in mind that a boat’s speed through the water and its speed over the ground are not the same. A tidal current of 2 knots against you turns a boat speed of 6 knots into only 4 knots over the ground, and a following current does the opposite. Aircraft have the same difference between airspeed and ground speed because of wind, so flight plans use both figures.

Common Mistakes to Avoid

• Saying knots per hour. A knot is already a speed.
• Treating knots as mph. 30 kn is 34.5 mph.
• Mixing nautical and statute miles. A nautical mile is 15% longer.
• Ignoring current or wind. Speed through water is not speed over ground.
• Using 1.15 for long trips. Use 1.15078 for accuracy.

Frequently Asked Questions

References & Sources