How to Convert Wind Speed From Knots to MPH
Traveling in a hot air balloon, a pilot overshoots his landing target by approximately two miles. How could this happen when his anemometer, which measures wind speed, showed wind speeds steady at 15? The pilot's error was in failing to recognize his measurements were in knots, not miles per hour (mph). Errors such as these are avoided by paying attention to units and knowing how to convert knots to mph. There are different wind speed conversion methods. Knowing how to estimate the conversion in your head can be useful.
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Instructions
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Calculate the conversion with a calculator. Using a calculator, multiply the number of knots by 1.1577945; the product is the wind speed in miles per hour.
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Calculate the conversion with pencil and paper. Multiply the same as you would with a calculator, except rounding 1.1577945 to the nearest hundredth, making it 1.16. This will give you a reasonable estimate and decrease multiplication time.
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Calculate the conversion with a wind speed conversion chart. Carry a wind speed conversion chart with you for reference. Though simple, this method might not be practical at all times.
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Calculate the conversion in your head. Converting knots to mph in your head can be done if you are good with mental math. Even if you lack tremendous mental math skills, a good estimate can be found by simply adding 15 percent to the wind speed in knots.
Do this by first rounding the knot wind speed to the nearest 10. For example, with a wind speed of 22 knots, first round down to 20. Next figure 10 percent of 20, which is 2, and add that to 20.
You now have 22 and need to add in the other 5 percent. Since you know 10 percent of 20 is 2, then 5 percent is half of 2, which is 1. Add 1 to 22 and you get the final answer of 23 mph.
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Tips & Warnings
Intuitively understanding what a knot is will allow you to bypass conversion techniques. If you can grasp the concept of what a mile per hour is, then after a little experience, a knot will be no different.
A knot is equal to one nautical mile per hour. A nautical mile is "equivalent to the distance spanned by one minute of arc in latitude" or 1,852 meters, according to a University of Arizona website.
Recognize the limitations to the mental math shortcut described in Step 4. In the example given, the precise conversion of 22 knots to mph is 25.5 mph. While this is not a bad estimate, depending on your application, this may not be precise enough.
