Knots to mph Converter

Created by Hanna Pamuła, PhD candidate
Reviewed by Dominik Czernia, PhD candidate
Last updated: Dec 15, 2021

If you're wondering how much is a knot, 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 is a knot or how fast it is. Also, you'll find an informative wind speed chart and all the formulas behind the wind speed units conversions.

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

Nautic mile definition

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)
  • 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 e.g.:

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

With this wind speed chart, you can assess the prevailing conditions and even estimate them in 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 2.5 2.88 4.63 4.22 1.29
Light breeze 4-7 mph 2 5 5.75 9.26 8.44 2.57
Gentle breeze 8-12 mph 3 7.5
10
8.63
11.51
13.89
18.52
12.66
16.88
3.86
5.14
Moderate breeze 13-18 mph 4 12.5
15
14.38
17.26
23.15
27.78
21.10
25.32
6.43
7.72
Strong breeze 25-31 mph 6 22.5
25
27.5
25.89
28.77
31.65
41.67
46.3
50.93
37.98
42.20
46.42
11.57
12.86
14.15
Moderate gale 32-38 mph 7 30
32.5
34.52
37.4
55.56
60.19
50.63
54.85
15.43
16.72
Fresh gale 39-46 mph 8 35
37.5
40
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 42.5
45
47.5
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
52.5
55
57.54
60.42
63.29
92.6
97.23
101.86
84.39
88.61
92.83
25.72
27.01
28.29
Violent storm 64-73 mph 11 57.5
60
62.5
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
67.5
70
74.8
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 is a knot - or for example 40 knots - 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 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 are equal to 46.03 mph. That's quite a lot!

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