How to convert miles per hour to knots
To convert miles per hour to knots, multiply the number of miles per hour by 0.86898 (or divide by 1.151).
Example: 30 mph = 26.069 kn.
Wind speeds in marine forecasts are given in knots.
Common mph to kn conversions
- 5 mph = 4.345 kn
- 10 mph = 8.69 kn
- 15 mph = 13.035 kn
- 20 mph = 17.38 kn
- 25 mph = 21.724 kn
- 30 mph = 26.069 kn
- 35 mph = 30.414 kn
- 40 mph = 34.759 kn
- 45 mph = 39.104 kn
- 50 mph = 43.449 kn
- 55 mph = 47.794 kn
- 60 mph = 52.139 kn
- 65 mph = 56.483 kn
- 70 mph = 60.828 kn
- 75 mph = 65.173 kn
- 80 mph = 69.518 kn
- 90 mph = 78.208 kn
- 100 mph = 86.898 kn
- 120 mph = 104.28 kn
- 128 mph = 111.23 kn
- 155 mph = 134.69 kn
- 200 mph = 173.8 kn
Miles Per Hour to Knots conversion chart
| mph | kn |
|---|---|
| 0.25 mph | 0.21724 kn |
| 0.5 mph | 0.43449 kn |
| 0.75 mph | 0.65173 kn |
| 1 mph | 0.86898 kn |
| 1.5 mph | 1.303 kn |
| 2 mph | 1.738 kn |
| 2.5 mph | 2.172 kn |
| 3 mph | 2.607 kn |
| 3.5 mph | 3.041 kn |
| 4 mph | 3.476 kn |
| 4.5 mph | 3.91 kn |
| 5 mph | 4.345 kn |
| 6 mph | 5.214 kn |
| 7 mph | 6.083 kn |
| 8 mph | 6.952 kn |
| 9 mph | 7.821 kn |
| 10 mph | 8.69 kn |
| 11 mph | 9.559 kn |
| 12 mph | 10.428 kn |
| 13 mph | 11.297 kn |
| 14 mph | 12.166 kn |
| 15 mph | 13.035 kn |
| 16 mph | 13.904 kn |
| 18 mph | 15.642 kn |
| 20 mph | 17.38 kn |
| 24 mph | 20.855 kn |
| 25 mph | 21.724 kn |
| 30 mph | 26.069 kn |
| 32 mph | 27.807 kn |
| 35 mph | 30.414 kn |
| 40 mph | 34.759 kn |
| 45 mph | 39.104 kn |
| 50 mph | 43.449 kn |
| 55 mph | 47.794 kn |
| 60 mph | 52.139 kn |
| 64 mph | 55.614 kn |
| 65 mph | 56.483 kn |
| 70 mph | 60.828 kn |
| 75 mph | 65.173 kn |
| 80 mph | 69.518 kn |
| 85 mph | 73.863 kn |
| 90 mph | 78.208 kn |
| 100 mph | 86.898 kn |
| 110 mph | 95.587 kn |
| 120 mph | 104.28 kn |
| 125 mph | 108.62 kn |
| 128 mph | 111.23 kn |
| 150 mph | 130.35 kn |
| 155 mph | 134.69 kn |
| 175 mph | 152.07 kn |
| 180 mph | 156.42 kn |
| 200 mph | 173.8 kn |
| 220 mph | 191.17 kn |
| 250 mph | 217.24 kn |
| 300 mph | 260.69 kn |
| 400 mph | 347.59 kn |
| 500 mph | 434.49 kn |
| 750 mph | 651.73 kn |
| 1,000 mph | 868.98 kn |
Metric vs. U.S. customary units
The United States uses U.S. customary units — inches, feet, miles, pounds, gallons and degrees Fahrenheit — for most everyday purposes. Canada officially adopted the metric system in the 1970s, so road signs, weather forecasts, gas pumps and food labels use kilometers, degrees Celsius, liters and grams. In practice many Canadians still use feet and inches for height, pounds for body weight and square feet for homes, which is why conversions come up constantly on both sides of the border.
Exact conversion factors
Since 1959 the inch, foot, yard, mile and pound have been defined in metric terms, so these conversions are exact, not approximations:
- 1 inch = 2.54 cm exactly, so 1 foot = 30.48 cm and 1 mile = 1.609344 km.
- 1 pound = 0.45359237 kg exactly; 1 ounce = 28.349523125 g.
- 1 U.S. gallon = 3.785411784 liters. The imperial gallon used in the U.K. is larger: 4.54609 liters.
- 1 acre = 4,046.8564224 m², and 1 hectare = 10,000 m² (about 2.471 acres).
Temperature is different because the scales have different zero points: °F = °C × 9/5 + 32 and °C = (°F − 32) × 5/9. Water freezes at 0 °C (32 °F) and boils at 100 °C (212 °F) at sea level, and −40 is the same in both scales.
Quick mental shortcuts
- Kilometers to miles: multiply by 0.6 (100 km ≈ 60 miles; the exact figure is 62.1).
- Kilograms to pounds: double it and add 10% (70 kg → 140 + 14 = 154 lb).
- Celsius to Fahrenheit: double it and add 30 for a rough estimate (20 °C → 70 °F; the exact answer is 68 °F).
- Liters to U.S. gallons: divide by 4 for a quick estimate (40 L ≈ 10 gallons; exactly 10.57).
Cooking and recipe conversions
U.S. recipes measure by volume — cups, tablespoons and teaspoons — while Canadian and most international recipes use milliliters and grams. A U.S. cup is about 237 mL, but Canadian "metric" measuring cups hold 250 mL, so the difference adds up in baking. For flour, sugar and butter, weighing in grams is more accurate than cups because the density of each ingredient differs.
Popular conversions
Pick a conversion below for a dedicated page with the formula, worked examples and a complete conversion chart.
Tips for accurate conversions
Keep full precision until the final step and round only the answer — rounding intermediate numbers can add noticeable errors, especially in recipes, construction and engineering. Always check which gallon, ounce or ton a source means: U.S. and imperial units share names but not sizes, and a "fluid ounce" measures volume while an "ounce" of weight measures mass. For temperatures, remember that a temperature difference converts differently from a temperature reading: a change of 10 °C equals a change of 18 °F, without adding 32.
Popular unit conversions
- Centimeters to Inches
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- Celsius to Kelvins
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- Milliliters to Liters
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- Imperial Gallons to Liters
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- Square Feet to Acres
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- Square Kilometers to Square Miles
- Square Miles to Square Kilometers
- Square Yards to Square Feet
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- Knots to Miles Per Hour
- Miles Per Hour to Knots
- Meters Per Second to Kilometers Per Hour
- Kilometers Per Hour to Meters Per Second
- Feet Per Second to Miles Per Hour
Frequently asked questions
How many centimeters are in an inch?
How do I convert kg to pounds?
What is the formula for Celsius to Fahrenheit?
Is a U.S. gallon the same as a Canadian gallon?
How many square feet are in a square meter?
Sources & methodology
This calculator was last reviewed on November 2, 2026. Figures are based on the following official and primary sources:
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