| Fahrenheit (°F) | Celsius (°C) |
|---|
To convert Fahrenheit to Celsius, subtract 32 then multiply by 5/9. The formula is:
The scales meet at −40°: the only temperature where both read the same value.
Key temperature landmarks in both scales:
To convert a temperature from Fahrenheit to Celsius, subtract 32 from the Fahrenheit value, then multiply by 5/9. For example, 98.6°F = (98.6 − 32) × 5/9 = 66.6 × 5/9 = 37°C — normal body temperature. Room temperature at 68°F = (68 − 32) × 5/9 = 20°C.
A quick mental shortcut: subtract 30 and halve the result for an approximate value. For example, 70°F: (70 − 30) / 2 = 20°C (actual is 21.1°C). For the reverse, see our Celsius to Fahrenheit converter.
Fahrenheit is the standard temperature scale in the United States. Celsius is used everywhere else — in Europe, Australia, Canada, and across science internationally. You'll need this conversion when reading US weather forecasts, understanding American cooking temperatures, interpreting US medical records, or simply making sense of temperatures from American TV shows, news, or websites.
Use the formula: °C = (°F − 32) × 5/9. First subtract 32, then multiply by 5/9 (or divide by 1.8). For example, 77°F = (77 − 32) × 5/9 = 45 × 5/9 = 25°C.
100°F = (100 − 32) × 5/9 = 68 × 5/9 = 37.78°C. This is just above normal body temperature (37°C / 98.6°F) and is considered a mild fever.
−40° is the same in both scales. At −40°F and −40°C, the two scales intersect. This is the only point where they agree. You can verify: (−40 − 32) × 5/9 = −72 × 5/9 = −40°C.
72°F = (72 − 32) × 5/9 = 40 × 5/9 = 22.2°C. This is a comfortable room temperature. Many thermostats are set around this value.
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