Absolute zero is the temperature 0 K, the starting point of the kelvin scale. NIST notes that the temperature 0 K is commonly referred to as absolute zero. Because 0 °C is 273.15 K, absolute zero on the Celsius scale is −273.15 °C.
Formula
°C = 0 K − 273.15 = −273.15
°F = −273.15 × 1.8 + 32 = −459.67
Example
Converting 0 K: 0 − 273.15 = −273.15 °C. In Fahrenheit: −273.15 × 1.8 = −491.67, plus 32 = −459.67 °F.
See the Celsius to Fahrenheit guide for the formula used here and Kelvin to Celsius for conversions.