Knots to mph Converter

Created by Hanna Pamuła, PhD
Reviewed by Dominik Czernia, PhD and Adena Benn
Last updated: Dec 03, 2022

If you're wondering how much a knot is, you're in the right place - this knots to mph converter can help you in clearing up your doubts. Type the value into the calculator, and in the blink of an eye, you'll get the answer - equivalent in mph, ft/s, m/s, and km/h. As our calculators are flexible tools, you can also convert mph to knot or any other wind speed unit. Keep reading if you want to know how many mph a knot is or how fast it is. Also, you'll find an informative wind speed chart and all the formulas behind the wind speed unit conversions.

How many mph is a knot and how fast is it? What is a nautical mile?

Nautic mile definition
Lidingo, VineetKumar, Yodin [CC BY-SA 4.0], via Wikimedia Commons

One knot is defined as 1 nautical mile per hour and:

  • 1.15078 miles per hour (approximately);
  • 1.852 kilometers per hour (exactly);
  • 1.68781 feet per second (approximately); and
  • 0.51444 meters per second (approximately).

Nautical miles and knots are the units used in meteorology, aviation, and nautical navigation. What's the difference between them? A nautical mile measures the distance, and a knot measures the speed.

One nautical mile historically was defined as one minute of latitude (1/60 of a degree of latitude), which is 1.852 kilometers. That's the average value, as the Earth is not a perfect sphere but a geoid.

Conversion formulas. Knots to mph and mph to knots

To convert between speed units, you can use our knots to mph converter or perform the conversion manually using the formulas:

  1. knots to mph and mph to knots
  • V(knots) = 0.868976 × V(mph);

  • V(mph) = 1.150779 × V(knots);

  1. knots and km/h
  • V(knots) = 0.539957 × V(km/h)

  • V(km/h) = 1.852 × V(knots)

  1. knots and ft/s
  • V(knots) = 0.592484 × V(ft/s)

  • V(ft/s) = 1.687810 × V(knots)

  1. knots and m/s
  • V(knots) = 1.943844 × V(m/s)

  • V(m/s) = 0.514444 × V(knots)

If you need conversion between other units (as there are 20 permutations and we present only 8 of them), take the coefficients from this table:

m/s

km/h

mph

knot

ft/s

1 m/s =

1

3.6

2.236936

1.943844

3.280840

1 km/h =

0.277778

1

0.621371

0.539957

0.911344

1 mph =

0.44704

1.609344

1

0.868976

1.466667

1 knot =

0.514444

1.852

1.150779

1

1.687810

1 ft/s =

0.3048

1.09728

0.681818

0.592484

1

Wind speed chart

Knowing how to convert knots to mph may be useful in many situations, such as:

  • Determining the boat speeds and airspeeds, be sure to check our true airspeed calculator).
  • Expressing tidal streams, river currents, and wind speeds.
  • Finding the optimal conditions for windsurfing or kiteboarding (6-30 knots is a range usually used, depending on the body weight, kite size, and how skilled you are). Check our kiteboarding calculator to become more skilled!

With this wind speed chart, you can assess the prevailing conditions and even estimate them on the Beaufort scale:

Description

Range

Beaufort number

knots

mph

km/h

ft/s

m/s

Calm

<1 mph

0

0

0

0

0

0

Light air

1-3 mph

1

2.50

2.88

4.63

4.22

1.29

Light breeze

4-7 mph

2

5.00

5.75

9.26

8.44

2.57

Gentle breeze

8-12 mph

3

7.50 10.00

8.63 11.51

13.89 18.52

12.66 16.88

3.86 5.14

Moderate breeze

13-18 mph

4

12.50 15.00

14.38 17.26

23.15 27.78

21.10 25.32

6.43 7.72

Strong breeze

25-31 mph

6

22.50 25.00 27.50

25.89 28.77 31.65

41.67 46.30 50.93

37.98 42.20 46.42

11.57 12.86 14.15

Moderate gale

32-38 mph

7

30.00 32.50

34.52 37.40

55.56 60.19

50.63 54.85

15.43 16.72

Fresh gale

39-46 mph

8

35.00 37.50 40.00

40.28 43.15 46.03

64.82 69.45 74.08

59.07 63.29 67.51

18.01 19.29 20.58

Strong gale

47-54 mph

9

42.50 45.00 47.50

48.91 51.79 54.66

78.71 83.34 87.97

71.73 75.95 80.17

21.86 23.15 24.44

Whole gale (storm)

55-63 mph

10

50.00 52.50 55.00

57.54 60.42 63.29

92.60 97.23 101.86

84.39 88.61 92.83

25.72 27.01 28.29

Violent storm

64-73 mph

11

57.50 60.00 62.50

66.17 69.05 71.92

106.49 111.12 115.75

97.05 101.27 105.49

29.58 30.87 32.15

Hurricane

74 mph

12

65.00 67.50 70.00

74.80 77.68 80.55

120.38 125.01 129.64

109.7 113.93 118.15

33.44 34.72 36.01

How to use knots to mph converter: 40 knots to mph example

If you are wondering how fast a knot is - or maybe it is 40 knots you wish to know - have a look at this short step-by-step example:

  1. Think about the unit you want to convert. Let's assume we want to change 40 knots into miles per hour.

  2. Type the value into the proper box. In our case, we need to enter 40 into the first part of the tool.

  3. That's it! Our knots to mph converter did the job! Now we know that 40 knots is equal to 46.03 mph. That's quite a lot!

Hanna Pamuła, PhD
knots
mph
km/h
ft/s
m/s
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