This scale sets the normal freezing point of water to 0 degrees Celsius and the normal boiling point of water to 100 degrees Celsius. Formerly called the Centigrade scale. A change of 1 degree Celsius equals a change of 9/5 = 1.8 degrees Fahrenheit. To convert a Celsius temperature to Fahrenheit, multiply by 9/5 and add 32. To convert a Celsius temperature to Kelvin, add 273.15