°C to °F Conversion: A Complete Guide

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You don’t have to be Einstein to use these fast and easy temperature conversion formulas

Co-authored by Joseph Quinones and Janice Tieperman

Last Updated: July 24, 2023 Fact Checked

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• Celsius to Fahrenheit Formula
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• Fahrenheit to Celsius Formula
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In most countries of the world, temperature is measured in degrees Celsius (°C). But what are you supposed to do when you have to measure something in Fahrenheit? With the help of two simple formulas, it’s easy to convert between Celsius and Fahrenheit (and vice versa) whenever you may need to. Simply plug the known temperature into the formula of your choice, and you’re good to go!

Things You Should Know

• Convert Celsius to Fahrenheit using the °F = (°C x 1.8) + 32 or °F = °C x ${\frac {9}{5}}$ + 32 formula.
• Convert Fahrenheit to Celsius with the °C = (°F - 32) x ${\frac {5}{9}}$ formula.

Steps

Method 1

Method 1 of 2:

Celsius to Fahrenheit Formula

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1. 1
   Use °F = (°C x 1.8) + 32 to convert Celsius to Fahrenheit. You may also use the equation °F = °C x ${\frac {9}{5}}$ + 32, which will produce the same answer since ${\frac {9}{5}}$ = 1.8. Plug any Celsius temperature into either equation to convert it to Fahrenheit.
2. 2
   Multiply the Celsius temperature by 1.8 to get started. Feel free to use a calculator if you’re crunched for time, or if you’d rather not do the math by hand.

   • Example 1: If the Celsius temperature is 20, multiply 20 by 1.8 to get 36. Alternatively, multiply the temperature (20) by 9, which equals 180, then divide 180 by 5, which equals 36.
   • Example 2: If the Celsius temperature is -10, multiply -10 by 1.8 to get -18. Alternatively, multiply the temperature (-10) by 9, which equals -90, and then divide by 5—this also gives you -18.
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3. 3
   Add 32 to the multiplied product to get the temperature in Fahrenheit. After multiplying the temperature by 1.8 (or by 9, then dividing by 5), add 32 to the answer.

   • Example 1: Add 32 to 36, which equals 68. So, 20°C is equal to 68°F.
   • Example 2: Add 32 to -18, which equals 14. So, -10°C is equal to 14°F.
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Method 2

Method 2 of 2:

Fahrenheit to Celsius Formula

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1. 1
   Use °C = (°F - 32) x $$ 5 9 {\displaystyle {\frac {5}{9}}} to convert Fahrenheit to Celsius. Simply plug in any Fahrenheit temperature and do the math to convert °F to °C.

   • You may also use the equation °C = (°F - 32) $\div {1.8}$, which will produce the same answer since dividing by 1.8 is the same as multiplying by ${\frac {1}{1.8}}$ = ${\frac {5}{9}}$
2. 2
   Subtract 32 from the Fahrenheit temperature to begin. The first step is to take away 32 from the temperature in Fahrenheit.

   • Example 1: If the Fahrenheit temperature is 90, subtract 32 from 90 to get 58.
   • Example 2: If the Fahrenheit temperature is -5, subtract 32 from -5 to get -37.
3. 3
   Multiply the subtracted difference by $$ 5 9 {\displaystyle {\frac {5}{9}}} to get the temperature in Celsius. After subtracting 32 from the temperature, multiply the answer you calculated by ${\frac {5}{9}}$ (or 0.55).

   • Example 1: Multiply ${\frac {58}{1}}$ by ${\frac {5}{9}}$, which gives you ${\frac {290}{9}}$. Divide this fraction to get 32.2—thus, 90°F is equal to 32.2°C.
   • Example 2: Multiply ${\frac {-37}{1}}$ by ${\frac {5}{9}}$, which gives you ${\frac {-185}{9}}$. Divide this fraction to get -20.5—thus, -5°F is equal to -20.5°C.
   • Keep in mind that 0.55 is actually short for 0.5555555555555556—so, only use the abbreviated decimal in your formula if you don’t need a precise conversion.
   • It is more accurate to divide the subtracted difference by 1.8 instead of multiplying by 0.55, as it does not incur the loss of precision.
     This is because ${\frac {1}{1.8}}$ = ${\frac {10}{18}}$ = ${\frac {5}{9}}$ exactly.
   • Example 1: Divide $58$ by $1.8$, which gives you 32.2—thus, 90°F is equal to 32.2°C, as above.
   • Example 2: Divide $-37$ by $1.8$, which gives you -20.5—thus, -5°F is equal to -20.5°C, as above.
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Calculator, Practice Problems, and Answers

Sample Celsius to Fahrenheit Calculator

Sample Convert Celsius to Fahrenheit Practice Problems

Sample Converting Celsius to Fahrenheit Practice Answers

Community Q&A

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• Question

  Confused! What is the 1.8 for?

  

  Janice Tieperman

  Community Answer

  The 1.8 in the Celsius to Fahrenheit formula is shorthand for the fraction 9/5 (since 9 divided by 5 equals 1.8). Converting the fraction to a decimal helps you complete the formula a bit more easily and quickly.

  Thanks! We're glad this was helpful.
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  Not Helpful 3 Helpful 5
• Question

  How do you convert a negative Celsius temperature to Fahrenheit (like -32 degrees)?

  

  Janice Tieperman

  Community Answer

  You'd use the same formula as shown above! Using the C x 1.8 +32 formula, multiply -32 by 1.8 to get -57.6. Then, add 32, which gives you -25.6—so, -32°C equals -25.6°F.

  Thanks! We're glad this was helpful.
  Thank you for your feedback.
  If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow

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• Question

  How do you convert 25°C into Fahrenheit?

  

  Janice Tieperman

  Community Answer

  Plug 25 into the formula C x 1.8 + 32. Start by multiplying 25 by 1.8, which gives you 45. From there, add 32 and 45 together to get 77. Therefore, 25°C is 77°F.

  Thanks! We're glad this was helpful.
  Thank you for your feedback.
  If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow

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Conversion Table

Celsius (°C)	Fahrenheit (°F)
-40	-40
-30	-22
-20	-4
-10	14
0	32
20	68
40	104
60	140
80	176
100	212