Ships and aircraft use knots because nautical miles (and therefore knots) are directly related to the Earth’s coordinates. One nautical mile equals one minute of latitude, which makes navigation calculations much more straightforward. When working with nautical charts or aeronautical maps that use latitude and longitude, speeds in knots allow for direct calculation of travel times without constant conversion. Additionally, using a standardized measurement system across international waters and airspace ensures clear communication between vessels, aircraft, and control centers worldwide, regardless of which country they’re from or which unit system (metric or imperial) they otherwise use.

Yes, a knot is slightly faster than a mile per hour. One knot equals approximately 1.15078 miles per hour, which means that speeds expressed in knots will be numerically smaller than the same speed expressed in MPH. For example, 30 knots equals approximately 34.5 MPH. This difference stems from the fact that a nautical mile (1,852 meters or approximately 6,076 feet) is longer than a statute mile (1,609 meters or 5,280 feet). The practical implication is that a vessel traveling at 20 knots is moving faster than a vehicle traveling at 20 MPH.

The Beaufort wind scale, developed in 1805 by Sir Francis Beaufort, relates observable wind effects to specific wind speed ranges. The scale ranges from 0 (calm) to 12 (hurricane force) and is defined using knots:

• Beaufort 0 (Calm): Less than 1 knot – Smoke rises vertically
• Beaufort 1 (Light air): 1-3 knots – Smoke drift indicates wind direction
• Beaufort 2 (Light breeze): 4-6 knots – Wind felt on face, leaves rustle
• Beaufort 3 (Gentle breeze): 7-10 knots – Leaves and small twigs in constant motion
• Beaufort 4 (Moderate breeze): 11-16 knots – Raises dust and loose paper
• Beaufort 5 (Fresh breeze): 17-21 knots – Small trees in leaf begin to sway
• Beaufort 6 (Strong breeze): 22-27 knots – Large branches in motion
• Beaufort 7 (Near gale): 28-33 knots – Whole trees in motion
• Beaufort 8 (Gale): 34-40 knots – Twigs break off trees
• Beaufort 9 (Strong gale): 41-47 knots – Slight structural damage occurs
• Beaufort 10 (Storm): 48-55 knots – Trees uprooted, considerable structural damage
• Beaufort 11 (Violent storm): 56-63 knots – Widespread damage
• Beaufort 12 (Hurricane force): 64+ knots – Severe destruction

This scale remains in use today for maritime weather forecasts and is particularly valuable because it connects abstract speed measurements to observable real-world effects.

For a quick mental conversion from knots to MPH, you can use the approximation that 1 knot equals about 1.15 MPH. In practice, this means:

• For a rough estimate: Add 15% to the knots value to get MPH
• For smaller values: Add 1 MPH for every 7 knots (approximately)
• For common values: Memorize that 10 knots ≈ 11.5 MPH, 20 knots ≈ 23 MPH, 50 knots ≈ 57.5 MPH

To convert from MPH to knots without a calculator, subtract about 13% from the MPH value. Alternatively, you can multiply the MPH value by 0.87 (a close approximation to the actual conversion factor of 0.868976). For example, 40 MPH × 0.87 = 34.8 knots.

Yes, virtually all countries worldwide use knots for maritime navigation and aviation, regardless of whether they otherwise use the metric or imperial measurement systems. This global standardization is crucial for international safety and communication. The International Civil Aviation Organization (ICAO) and the International Maritime Organization (IMO) both establish standards that specify the use of knots for speed measurements. This means that a pilot flying from a metric country like France to an imperial-measurement country like the United States will use knots throughout the journey, and similarly, ships traveling between different countries will consistently communicate their speeds in knots. This universal standard helps prevent dangerous miscommunications and confusion in international transportation.