Celsius to Fahrenheit, Both Directions
Type a temperature on either side. Works below zero, above boiling, and everywhere between.
20 °C68 °F
The Celsius to Fahrenheit Formula
Multiply by 1.8, add 32. Written out: °F = °C × 1.8 + 32. Reversing it, subtract 32 from the Fahrenheit reading and multiply by 5/9 to land back on Celsius.
Worked example
Take 37 °C, normal body temperature. 37 × 1.8 gives 66.6, and 66.6 + 32 gives 98.6 °F, the number printed on American thermometers. The same two steps turn a 20 °C room into 68 °F.
The point where both scales agree
Minus 40 is the crossing point: -40 °C and -40 °F are the same temperature. That quirk makes a handy sanity check for any converter, this one included. Type -40 on either side and watch the other match it.
A rough rule for weather
Double the Celsius and add 30. For 15 °C that estimates 60 °F; the exact answer is 59. Close enough to pick a jacket, not close enough to calibrate an oven, which is what the full formula is for.