How to Convert Fahrenheit to Celsius With an Equation
Celsius and Fahrenheit are the two most common standards of temperature measurement in the world. You can convert from Fahrenheit to Celsius or Celsius to Fahrenheit using simple equations.
Fahrenheit to Celsius Equation

To convert a Fahrenheit temperature into Celsius, subtract 32 from the temperature and then divide by 1.8. This conversion is shown by the following equation, in which Ft is the Fahrenheit temperature, and Ct is Celsius temperature:
Ct = (Ft  32)/1.8
Say you're baking bread at 375 degrees Fahrenheit, and want to know the temperature in Celsius. Subtract 32 from 375, and divide by 1.8:
Ct = (375  32)/1.8
Ct = 343/1.8
Ct = 190.56Your oven has a temperature of 190.56 degrees Celsius.
Celsius to Fahrenheit Equation

You can reverse the conversion formula to convert from Celsius to Fahrenheit. To convert in this direction, multiply the Celsius temperature by 1.8, and then add 32:
Ft = 1.8Ct + 32
Take a liquid boiling at 120 degrees Celsius. What temperature is it in Fahrenheit? Multiply 120 by 1.8, and then add 32:
Ft = 1.8 x 120 + 32
Ft = 216 + 32
Ft = 248This liquid has a temperature of 248 degrees Fahrenheit.
1.8 and 9/5

The number 1.8 is equal to 9/5, so you can use 9/5 in place of 1.8 in your equations:
Ct = (Ft  32) x 5/9
Ft = (9/5 x Ct) + 32This can be useful if you don't have a calculator and are dealing with Celsius temperatures that are multiples of 5. To convert 20 degrees C to Fahrenheit, you can divide 20 by 5, getting 4, and then multiply by 9, getting 36. The result is the same as if you'd multiplied 20 by 1.8. Add 32 to get Fahrenheit temperature:
Ft = 36 + 32 = 68
So 20 degrees C is 68 degrees F.
References
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