Quote:
Originally Posted by McG
bob and doug McKenzie say that you just double imperial and add 30 to convert to metric, and that's ok by me.
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That generally works well enough if you're dealing with normal environmental temperatures. It doesn't work as well when converting things like cooking temperatures.
Room temperature is 20°C or 68°F. Using the double it and add 30 rule, it converts to 70, which is close enough.
Freezing is 0°C and 32°F. Using x2+30, you get 30. Again, close enough.
As the temperatures get more extreme, the conversion becomes less accurate. In those cases, all you really need to know is that anything below 0°F is way too cold to be outside for any amount of time, and anything above 100°F is way too hot to be outside for any amount of time.
If you somehow had an oven that only had temperatures in Celsius and a recipe that only had temperatures in Fahrenheit, you wouldn't want to use the x2+30 conversion in that case. 375°F is 190.6°C, but using that rough conversion, you'd only get 172.5.