Temperature

Celsius-Fahrenheit

Formula

Mental calculation trick

Celsius-Fahrenheit

Multiply the celsius value by 2 and add 30.

• ex. 15° C is estimated at 60° F ($15\times2 + 30$) (actual 59°F)
• The higher the values we are converting, the more off our estimations will be. At 40° C, our mental trick gives us a value in Fahrenheit which is equal to 43° C.
  • therefore as long as we are talking about typical temperatures found on Earth, then at worst we'll be within about 3°C

Fahrenheit-Celsius

Subtract 30 from the Fahrenheit number and divide the result by 2

• ex. 100° F is estimated at 35° C (${100 - 30} \over 2$) (actual 37.7°C)