Celsius to Fahrenheit: Formula & Quick Conversions

To convert Celsius to Fahrenheit, use °F = (°C × 9/5) + 32. So 20°C = (20 × 1.8) + 32 = 68°F. To go back, °C = (°F − 32) × 5/9. Here's the formula, a quick mental shortcut, common reference points, and a free temperature converter.

The conversion formulas

• C → F: °F = (°C × 9/5) + 32
• F → C: °C = (°F − 32) × 5/9

The Temperature Converter flips between Celsius, Fahrenheit, and Kelvin instantly.

Fast mental math

For a rough Celsius-to-Fahrenheit estimate: double the Celsius and add 30. 20°C → 40 + 30 = 70°F (actual 68°F — close enough for weather). It drifts at extremes but is handy day to day.

Reference points worth memorizing

• 0°C = 32°F — water freezes
• 37°C = 98.6°F — body temperature
• 100°C = 212°F — water boils
• −40°C = −40°F — the one point where the scales meet

Bottom line

°F = (°C × 9/5) + 32, or double-and-add-30 for a quick estimate. For exact conversions across weight, length, and more, see everyday unit conversions or use the Temperature Converter.