Temperature Conversion Formulas
°C = (°F − 32) × 5/9
°F = °C × 9/5 + 32
K = °C + 273.15
°C = K − 273.15
Quick Mental Math
- °F to °C (approximate): Subtract 30, divide by 2. Example: 80°F → (80-30)/2 = 25°C (actual: 26.7°C)
- °C to °F (approximate): Double it, add 30. Example: 20°C → 20×2+30 = 70°F (actual: 68°F)
- Equal point: −40°F = −40°C (the one temperature where both scales match)
Frequently Asked Questions
What is absolute zero? 0 K = −273.15°C = −459.67°F — the lowest possible temperature where particles have minimal kinetic energy.
Which countries use Fahrenheit? The United States, Bahamas, Cayman Islands, Palau, and a few others use Fahrenheit. Most of the world uses Celsius.