What is system of centigrade to Fahrenheit conversion calculator?

Substract 32 from the Fahrenheit reading and divide the result by 1,8.

Example: 212°F minus 32 = 180°F

180°F / 1,8 = 100°C

Origin of the Fahrenheit scale is from temperature that cattle can survive outside.

0 deg to 100 deg. Not very scientific...