Learn the simple formula to convert any temperature from Celsius to Fahrenheit — and back — with practical examples and quick reference points.
Step-by-Step Guide
Learn the Formula
To convert Celsius (°C) to Fahrenheit (°F), multiply by 9/5 and add 32. Formula: **°F = (°C × 9/5) + 32**. To convert back: **°C = (°F − 32) × 5/9**.
Work Through an Example
Convert 25°C to Fahrenheit: 25 × 9/5 = 45, then 45 + 32 = 77°F. Convert 98.6°F to Celsius: 98.6 − 32 = 66.6, then 66.6 × 5/9 = 37°C (normal body temperature).
Use the Simplified Mental Math Trick
For a quick approximation: double the Celsius value and add 30. Example: 20°C → 20 × 2 + 30 = 70°F (actual: 68°F). This is handy for everyday estimates but not for precision.
Memorise Key Reference Points
0°C = 32°F (water freezes) | 20°C = 68°F (comfortable room) | 37°C = 98.6°F (body temp) | 100°C = 212°F (water boils). These anchors make mental estimates fast.
Use a Converter for Precision
For exact results — especially in cooking, science, or engineering — use our Temperature Converter tool. It handles Celsius, Fahrenheit, Kelvin, and more instantly.
Try Our Free Tool
Temperature Converter
Frequently Asked Questions
Q: Is there a temperature where Celsius and Fahrenheit are the same?
A: Yes — at −40 degrees. Both scales intersect: −40°C = −40°F.
Q: Why does the US use Fahrenheit?
A: The Fahrenheit scale was developed by Daniel Gabriel Fahrenheit in 1724 and was widely adopted in English-speaking countries. While most of the world switched to Celsius in the 20th century, the US retained Fahrenheit.
Q: How do I convert Celsius to Kelvin?
A: Simply add 273.15: K = °C + 273.15. Kelvin is an absolute temperature scale starting at absolute zero, used in science and engineering.