Guides/Fahrenheit to Celsius quick formula
Fahrenheit to Celsius quick formula
Convert °F to °C by subtracting 32, then multiplying by 5/9. For rough weather sense, subtract 30 and halve.
Exact formula
°C = (°F − 32) × 5/9
Reverse (°C → °F): °F = °C × 9/5 + 32. Full pair:Celsius ↔ Fahrenheit explained. Mental tricks both ways:temperature tricks without a calculator.
Quick estimate
- Subtract 30, then divide by 2 ≈ °C (good for mild weather).
- Anchors: 32 °F = 0 °C, 68 °F ≈ 20 °C, 98.6 °F ≈ 37 °C, 212 °F = 100 °C.
Worked examples
- 50 °F: (50 − 32) × 5/9 = 18 × 5/9 = 10 °C.
- 77 °F: (77 − 32) × 5/9 = 45 × 5/9 = 25 °C.
- 350 °F oven: (350 − 32) × 5/9 = 318 × 5/9 = 176.7 °C (≈ 180 °C in many recipes).
- Estimate: 68 °F → −30 → 38 → ≈ 19 °C (exact 20 °C).
Common mistakes
- Multiplying by 5/9 before subtracting 32.
- Using ×9/5 when going °F → °C.
- Treating the −30/halve trick as lab-accurate.
Convert online
Use theUnit ConverterTemperature tab for exact °F, °C, and K.