-18 degrees Celsius would be equal to -64.4 F and 18 degrees Celsius would be equal to 64.4 F.
19 degrees Celsius is equal to 66.2 F in Fahrenheit.
20 degrees Celsius is equal to 68.0 F in Fahrenheit.
21 degrees Celsius is equal to 69.8 F in Fahrenheit.
And 22 degrees Celsius is equal to 71.6 in Fahrenheit.
Fahrenheit to Celsius, subtract 30 then divide by 2.
Celsius to Fahrenheit, multiply by 2 then add 30.
Celsius is 1.8 times larger than Fahrenheit.
To put it another way, 1 degree Fahrenheit is 5/9 degree Celsius.
Despite the pretty large differences between one another, these two temperature scales intersect at -40 degrees, meaning that -40 degrees Fahrenheit is the same as -40 degrees Celsius.