Farenheit to Celcius, (F - 32) / 1.8 = ~C Lazy man's version is just to take (F - 32) and halve it. Will give you slightly below actual temp. About the only time this whole Fahrenheit/Celsius thing mixes me up is figuring out rise over ambient temps. Even then, I have an infrared thermometer. I just shoot the front of my case with it (main intakes) and use that instead.