45 Knots to MPH – Answer and Calculator Tool

45 knots is equal to approximately 51.8282 miles per hour (mph).

The conversion from knots to mph involves multiplying the knot value by a fixed factor because knots measure speed based on nautical miles per hour, whereas mph measures speed in statute miles per hour. This difference requires a conversion factor to translate between the units accurately.

Conversion Tool

Conversion Formula

To convert knots to miles per hour, multiply the number of knots by 1.150779448. This factor comes from the difference between a nautical mile and a statute mile. A nautical mile is defined as exactly 1,852 meters, while a statute mile is 1,609.344 meters. Since knots measure nautical miles per hour, we adjust to miles per hour using:

mph = knots × 1.150779448

Example: To convert 45 knots:

• Multiply 45 by 1.150779448
• 45 × 1.150779448 = 51.78557516
• The result is about 51.79 mph

This formula allows you to switch from nautical speed to land speed, which is more familiar in everyday use.

Conversion Example

• Example: 30 knots to mph
  • Multiply 30 by 1.150779448
  • 30 × 1.150779448 = 34.52338344 mph
  • The final result rounds to 34.52 mph
• Example: 55 knots to mph
  • Multiply 55 by 1.150779448
  • 55 × 1.150779448 = 63.29286964 mph
  • Rounded result is 63.29 mph
• Example: 12.5 knots to mph
  • Multiply 12.5 by 1.150779448
  • 12.5 × 1.150779448 = 14.3847431 mph
  • Rounded to 14.38 mph
• Example: 60 knots to mph
  • Multiply 60 by 1.150779448
  • 60 × 1.150779448 = 69.04676688 mph
  • Rounded to 69.05 mph

Conversion Chart

The chart below shows knots values from 20.0 to 70.0 converted into miles per hour. You can find the mph equivalent quickly without calculation by locating the knots value:

Related Conversion Questions

• How fast is 45 knots in miles per hour exactly?
• What mph speed corresponds to 45 knots on a boat?
• Is 45 knots faster than 50 mph or slower?
• How do I convert 45 knots into miles per hour by hand?
• What is the mph equivalent of traveling 45 knots?
• Does 45 knots equal more or less than 60 mph?
• What’s the formula to change 45 knots into mph?

Conversion Definitions

Knots: A unit for speed used in maritime and aviation, knots measure one nautical mile per hour. One nautical mile equals approximately 1,852 meters, based on the Earth’s circumference. Knots are preferred in navigation due to their direct relation to latitude and longitude measurements.

Miles per Hour (mph): A common speed unit in countries using imperial system, mph represents the number of statute miles traveled in one hour. One mile equals 1,609.344 meters. This unit is often used for road speeds, aviation, and other land-based transportation.

Conversion FAQs

Why is the factor 1.150779448 used to convert knots to mph?

The factor 1.150779448 comes from the ratio between a nautical mile and a statute mile. Since a knot is one nautical mile per hour, converting to miles per hour means adjusting for the different lengths of the nautical and statute miles. Multiplying knots by this factor converts the speed correctly.

Can I use the same conversion for kilometers per hour?

No, knots to kilometers per hour require a different factor because kilometers and miles differ in length. To convert knots to km/h, multiply knots by 1.852. Using the mph factor for km/h would result in an inaccurate speed.

Is 45 knots considered fast for a boat?

For recreational boats, 45 knots is quite fast. Many speedboats operate between 20 and 50 knots. However, commercial ships and large vessels travel slower for safety and efficiency, so 45 knots is faster than most typical ship speeds but common in high-speed boats or racing.

Does wind speed measured in knots convert the same to mph?

Yes, wind speed in knots converts to mph using the same factor because wind speed’s units measure distance over time similarly to vessel speeds. Multiply by 1.150779448 to get miles per hour wind speed.

Are there any rounding errors when converting knots to mph?

Small rounding errors can occur because the conversion factor is a decimal with many digits. Rounding the result to a few decimal places is standard, but the difference is minimal and usually not noticeable in practical use.

Last Updated : 22 July, 2025

Sandeep Bhandari

Sandeep Bhandari holds a Bachelor of Engineering in Computers from Thapar University (2006). He has 20 years of experience in the technology field. He has a keen interest in various technical fields, including database systems, computer networks, and programming. You can read more about him on his bio page.