Temperature conversions
°F = °C × 9⁄5 + 32 · °C = (°F − 32) × 5⁄9 · K = °C + 273.15
Key reference points: water freezes at 0 °C = 32 °F = 273.15 K and boils at 100 °C = 212 °F. Body temperature is ~37 °C (98.6 °F). −40° is the one temperature where Celsius and Fahrenheit read the same.
Celsius, Fahrenheit and Kelvin
Enter a value in any scale and see all three at once. The core formulas are °F = °C × 9/5 + 32 and K = °C + 273.15. For a quick mental estimate of Celsius to Fahrenheit, double and add 30.