Converting Fahrenheit to Celsius doesn’t require a calculator. Here are some easy-to-remember temperatures if you’re accustomed to Fahrenheit temperatures…

- 10F ≈ -10C
- 32F = 0C (melting point of water)
- 40F ≈ 4C
- 70F ≈ 20C
- 100F ≈ 40C

**Converting Fahrenheit to Celsius**

- Take your Fahrenheit temperature, and subtract 32 from it. Let’s say the temperature is 50F. Our result is then 50 – 32 = 18.
- Multiply the result by 5. In our example, we do the multiplication and get 18 x 5 = 90.
- Divide the result by 9 to get our final Celsius result, 90 ÷ 9 = 10C.

**Fahrenheit to Celsius formula**: (F-32) x 5 ÷ 9 = C

**Convert Celsius to Fahrenheit**

- Take your Celsius temperature, and multiply by 9. Let’s say the temperature is 25C. Our result is then 25 x 9 = 225.
- Divide the result by 5. In our example, we do the division and get 225 ÷ 5 = 45.
- Add 32 to the result to get our final Fahrenheit result, 45 + 32 = 77.

**Celsius to Fahrenheit formula: **C x 9 ÷ 5 + 32 = F

**Why is -40F = -40C?**

Oddly enough, -40F is not colder than -40C. Yes, they are both really cold, but they are also exactly the same temperature. Let’s use the formulas from above and try it out.

Convert -40F to Celsius

- (F-32) x 5 ÷ 9
- (-40-32) x 5 ÷ 9
- -72 x 5 ÷ 9 = -40

Convert -40C to Fahrenheit

- (C x 9 ÷ 5) + 32
- (-40 x 9 ÷ 5) + 32
- -72 + 32 = -40

Exactly the same!

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