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Six Methods:Converting Fahrenheit to CelsiusConverting Celsius to FahrenheitConverting Celsius to KelvinConverting Kelvin to CelsiusConverting Kelvin to FahrenheitConverting Fahrenheit to Kelvin

You can convert degrees Fahrenheit to degrees Celsius or vice versa by using simple addition, subtraction, multiplication, and division. Next time you’re given the temperature in the wrong scale, you’ll be able to convert it in just a matter of seconds!

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EditMethod 1 of 6: Converting Fahrenheit to Celsius

  1. 1
    Understand the scales. The Fahrenheit and Celsius scales begin at a different number—where 0° Celsius is freezing, that equivalent temperature in Fahrenheit is 32°. In addition to starting at a different temperature, the two scales rise at different rates as well. For instance, the range from freezing to boiling in degrees Celsius is 0-100°, and the same range in degrees Fahrenheit is 32-212°.[1]
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  2. Convert Between Fahrenheit and Celsius Step 1.jpg
    2
    Subtract 32 from the Fahrenheit temperature. Since freezing for Fahrenheit is 32 and freezing for Celsius is 0, you begin the conversion by subtracting 32 from the Fahrenheit temperature.[2]
    • For example, if your initial Fahrenheit temperature is 74°F, just subtract 32 from 74. 74-32 = 42.[3]
  3. Convert Between Fahrenheit and Celsius Step 2.jpg
    3
    Divide the result by 1.8. The range for freezing to boiling in Celsius is 0-100 whereas it's 32-212 in Fahrenheit. This is the same as saying that for every 180° Fahrenheit range, there is only a 100° Celsius range. You can express that as 180/100, which when simplified equals 1.8, so to finish the conversion you must divide by 1.8.
    • For the example from step one, divide your result, 42, by 1.8. 42/1.8 = 23°C. Therefore, 74°F can be converted to 23°C.
    • Note that 1.8 is the equivalent of 9/5. If you don't have a calculator or prefer working with fractions, you can divide your result from the first step by 9/5 instead of 1.8.

EditMethod 2 of 6: Converting Celsius to Fahrenheit

  1. 1
    Understand the scales. Since the same rules in the scale differences apply when converting Celsius to Fahrenheit as the opposite, you'll still be using the difference of 32 and the scale difference of 1.8. You just use them in the reverse order.
  2. Convert Between Fahrenheit and Celsius Step 3.jpg
    2
    Multiply the Celsius temperature by 1.8. If instead, you want to convert the temperature from degrees Celsius to degrees Fahrenheit, you can simply reverse the process. Begin by multiplying the Celsius temperature by 1.8.[4]
    • For example, if you're working with the temperature 30°C, you should first multiply it by 1.8, or 9/5. 30 x 1.8 = 54.[5]
  3. Convert Between Fahrenheit and Celsius Step 4.jpg
    3
    Add 32 to the result. Now that you have corrected for the differences in scale, you still must correct for the difference in starting points as in step one. To do this, add 32 to the Celsius x 1.8 temperature, and you will have the final temperature in degrees Fahrenheit.
    • Add 32 to 54, which was the result from step 3. 54 + 32 = 86°F. Therefore, 30°C is equivalent to 86°F.

EditMethod 3 of 6: Converting Celsius to Kelvin

  1. 1
    Understand the scales. Scientists understand the Celsius scale as derived from the Kelvin scale.[6] Though the gaps between Celsius and Kelvin are even larger than the gaps between Celsius and Fahrenheit, one thing that Celsius and Kelvin have in common is that they rise at the same rate. Whereas the ratio for Celsius to Fahrenheit is 1:1.8, the ratio for Celsius to Kelvin is 1:1.[7]
    • If it seems odd that freezing for Kelvin would be such a high number--273.15--it's because the Kelvin scale is based around absolute zero, which is 0°K.
  2. Convert Between Fahrenheit and Celsius Step 5.jpg
    2
    Add 273.15 to your Celsius temperature. Though 0°C is the freezing temperature of water, scientists actually understand 0°C as 273.15°K.[8] Since the two scales rise at the same rate, then converting Celsius to Kelvin always means simply adding 273.15.
    • For example, if you're working with the temperature 30°C, just add 273.15 to that. 30 + 273.15 = 303.15°K.

EditMethod 4 of 6: Converting Kelvin to Celsius

  1. 1
    Understand the scales. The 1:1 ratio for each degree Celsius and Kelvin still applies while converting Kelvin to Celsius. You mostly need to remember the 273.15 number and perform the opposite operation as when you convert Celsius to Kelvin.
  2. Convert Between Fahrenheit and Celsius Step 6.jpg
    2
    Subtract 273.15 from your Kelvin temperature. If instead you need to convert the temperature from Kelvin to Celsius, you can simply reverse the operation and subtract 273.15. Let’s say you're starting with a Kelvin temperature of 280°K. Just subtract 273.15 from 280 to get the Celsius temperature. 280K - 273.15 = 6.85°C.

EditMethod 5 of 6: Converting Kelvin to Fahrenheit

  1. 1
    Understand the scales. One of the most important things to remember while converting between Kelvin and Fahrenheit is the rise ratio. Since Kelvin has a 1:1 ratio with Celsius, it has the same ratio to Fahrenheit as Celsius, which is to say that for every 1°K, Fahrenheit changes by 1.8°F.[9]
  2. Convert Between Fahrenheit and Celsius Step 7.jpg
    2
    Multiply by 1.8. In order to correct for the 1K:1.8F scale, the first step in converting Kelvin to Fahrenheit is multiplying by 1.8.
    • Let’s say you're starting with a temperature of 295°K. Just multiply that number by 1.8. 295 x 1.8 = 531.
  3. Convert Between Fahrenheit and Celsius Step 8.jpg
    3
    Subtract 459.7 from the result. Just as we must correct for the starting point of the scale by adding 32 when converting Celsius to Fahrenheit, we must also do the same when converting Kelvin to Fahrenheit. However, 0°K = -459.7°F.[10] Since the number we have to add is actually a negative number, that means we must simply subtract the number.
    • Just subtract 459.7 from 531. 531 - 459.7 = 71.3 °F. Therefore, 295°K = 71.3 °F.

EditMethod 6 of 6: Converting Fahrenheit to Kelvin

  1. Convert Between Fahrenheit and Celsius Step 9.jpg
    1
    Subtract 32 from the Fahrenheit temperature. On the other hand, to convert a Fahrenheit temperature to a Kelvin temperature, it’s easiest to convert to Celsius and then make the conversion to Kelvin from there. This means we begin by subtracting 32.
    • Let’s say the temperature is 82°F. Subtract 32 from that number. 82 - 32 = 50.
  2. Convert Between Fahrenheit and Celsius Step 10.jpg
    2
    Multiply that number by 5/9. When converting Fahrenheit to Celsius, the next step is to multiply by 5/9–or divide by 1.8 if you have a calculator around.
    • 50 x 5/9 = 27.7, which is the Fahrenheit temperature now converted to Celsius.
  3. Convert Between Fahrenheit and Celsius Step 11.jpg
    3
    Add 273.15 to this number. Since the difference between Celsius and Kelvin = 273.15, you can then get the Kelvin temperature by adding 273.15.
    • 273.15 + 27.7 = 300.8. Therefore, 82°F = 300.8°K.
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EditTips

  • Here are some key conversion numbers worth remembering:
    • Water freezes at 0°C or 32°F.
    • Body temperature is typically 37°C or 98.6°F.
    • Water boils at 100°C or 212°F.
    • At -40, both temperatures are equal.
  • When targeting an international audience do not use the words 'centigrade' or 'celsius'. Use 'degrees Celsius' instead.
  • Double check your math, it will make you more confident in your final answer.
  • You can also use the formula C = 5/9(F - 32) to convert Fahrenheit to Celsius, and 9/5C = F - 32 to convert Celsius to Fahrenheit. These formulas are short versions of this equation: C/100=F-32/180. As freezing point is within the range of 212 in the F thermometer, we have to subtract it, 32ºF, from F temperatures ( F-32 ) and we also have to subtract it from 212, and that's how we get the 180 cipher. This been done, both intervals are equal and we get the "long version" equation.
  • Remember that Kelvin is always 273.15° more than Celsius.

EditRelated wikiHows

How to
Estimate Celsius Temperatures in Fahrenheit

How to
Convert Kelvin to Fahrenheit or Celsius

EditSources and Citations

  1. ↑ http://www.mathsisfun.com/temperature-conversion.html
  2. ↑ http://www.mathsisfun.com/temperature-conversion.html
  3. ↑ http://www.mathsisfun.com/temperature-conversion.html
  4. ↑ http://www.mathsisfun.com/temperature-conversion.html
  5. ↑ http://www.mathsisfun.com/temperature-conversion.html
  6. ↑ http://www.metric-conversions.org/temperature/fahrenheit-to-celsius.htm
  7. ↑ http://www.metric-conversions.org/temperature/fahrenheit-to-celsius.htm
  8. ↑ http://www.metric-conversions.org/temperature/fahrenheit-to-celsius.htm
  9. ↑ http://www.metric-conversions.org/temperature/fahrenheit-to-celsius.htm
  10. ↑ http://www.rapidtables.com/convert/temperature/how-kelvin-to-fahrenheit.htm

Article Info

Categories: Physics | Conversion Aids

In other languages:

Français: Comment convertir les degrés Celsius en degrés Fahrenheit ou en kelvins et vice versa, Italiano: Come Convertire da Fahrenheit a Celsius, Español: Cómo hacer conversiones de Fahrenheit y Celsius, Deutsch: Fahrenheit in Celsius umrechnen, Português: Como Fazer a Conversão entre Fahrenheit e Celsius, Nederlands: Omrekenen tussen Celsius en Fahrenheit, Русский: конвертировать единицы измерения температуры, Bahasa Indonesia: Mengkonversi Fahrenheit dan Celcius, 日本語: 華氏と摂氏の温度を換算する（する）方法, 中文: 在华氏温度和摄氏温度间转换

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