Fahrenheit to Celsius

Degrees Fahrenheit and degrees Celsius

The Fahrenheit scale puts water's freezing point at 32 °F and boiling at 212 °F; one Fahrenheit degree is 5/9 of a Celsius degree. The United States and a few Caribbean countries use Fahrenheit for weather, ovens and body temperature.

The Celsius scale is defined from the kelvin: t/°C = T/K − 273.15, so water freezes at about 0 °C and boils at about 100 °C at sea level. Weather, cooking and body temperature are given in Celsius almost everywhere except the United States.

Worked example

Convert 98.6 °F with °C = (°F − 32) × 5/9: the result is 37 °C. Likewise 50 °F = 10 °C.

Estimating in your head

Subtract 30 and halve: 70 °F → about 20 °C (exactly 21.1 °C). The estimate stays within about 2 °C from 20 °F to 85 °F.

Going the other way

To convert degrees Celsius to degrees Fahrenheit, type in the right-hand box; the page solves the same formula backwards. The swap button between the boxes opens the reverse page.

°C = (°F − 32) × 5/9

Temperature scales have different zero points as well as different degree sizes, so the conversion scales and shifts; there is no single factor. The page converts through kelvin using the exact definitions in NIST SP 811. Results drop binary floating-point noise beyond 15 significant digits and display at the precision you choose (6 significant figures by default). Copy result copies the full value.