Mental calculation trick
Multiply the celsius value by 2 and add 30.
- ex. 15° C is estimated at 60° F () (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
Subtract 30 from the Fahrenheit number and divide the result by 2
- ex. 100° F is estimated at 35° C () (actual 37.7°C)