Nautical Mile Calculator

What is a Nautical Mile?

A nautical mile (symbol: nmi or NM) is a unit of length used in air and marine navigation. It is defined as exactly 1,852 meters (about 6,076 feet). This measurement is based on the circumference of the Earth—one nautical mile equals one minute of arc along any meridian.

Why Use Nautical Miles?

Nautical miles are the international standard for maritime and aviation navigation because:

• Consistency with Earth's geometry: One nautical mile equals one minute of latitude, making chart reading and navigation calculations simpler
• Universal standard: Used worldwide by mariners, pilots, and meteorologists
• Practical for navigation: Easy to measure distances on nautical charts

Conversion Formulas

Distance Conversions

Speed Conversions

Speed, Distance, and Time Formulas

The relationship between speed, distance, and time:

• Distance = Speed × Time
• Speed = Distance ÷ Time
• Time = Distance ÷ Speed

When using nautical units: Distance in nautical miles, Speed in knots, Time in hours

Example Calculations

Example 1: A ship traveling at 20 knots for 5 hours

Distance = 20 knots × 5 hours = 100 nautical miles
= 185.2 km = 115.08 statute miles

Example 2: A 60 nautical mile journey at 15 knots

Time = 60 nm ÷ 15 knots = 4 hours

Common Distance References

What is a Knot?

A knot (symbol: kn or kt) is a unit of speed equal to one nautical mile per hour. The term comes from the historical practice of measuring a ship's speed by counting knots on a rope paid out over a fixed time.

Navigation Note: This calculator provides mathematical conversions. For actual navigation, always use proper nautical charts and verified navigation tools. Weather, currents, and other factors affect real-world travel times.