Turn any Celsius reading into Fahrenheit.
Type a temperature in Celsius to see it in Fahrenheit and Kelvin instantly. The Fahrenheit box converts back the other way, so it works in both directions, and it handles temperatures below zero correctly.
Your temperature
Enter a value in either box. Negatives are fine, for example -40 or -273.15.
What this reading means
Common temperatures
| Celsius | Fahrenheit | What it is |
|---|
Celsius and Fahrenheit explained
The Celsius-to-Fahrenheit Formula
To convert Celsius to Fahrenheit: F = C × 9/5 + 32. The 9/5 ratio (or 1.8) accounts for the fact that each Celsius degree is 1.8 times larger than each Fahrenheit degree. The +32 shifts the scales so that 0 °C = 32 °F (water's freezing point).
Why Two Scales Exist
Anders Celsius proposed his scale in 1742, anchoring 0 to water's freezing point and 100 to boiling point at sea level. Daniel Gabriel Fahrenheit (1724) used 32 for the freezing point of brine ice and 96 for normal body temperature. Most countries adopted Celsius; the US still uses Fahrenheit for weather and everyday temperature.
Reference Temperatures
-40 °C = -40 °F (the only point where they meet). 0 °C = 32 °F (water freezes). 20 °C = 68 °F (room temperature). 37 °C = 98.6 °F (body temperature). 100 °C = 212 °F (water boils at sea level). 200 °C = 392 °F (oven for roasting).
Mental Math Shortcut
For quick estimates: double the Celsius value and add 30. For 20 °C: 20×2 + 30 = 70 °F (actual 68). Accurate within ~3°F for typical temperatures. The exact formula (×1.8 + 32) is the calculator's method.
Common questions
What is 20 °C in Fahrenheit?
20 °C equals 68 °F (20 × 1.8 + 32 = 36 + 32 = 68).
Why do Celsius and Fahrenheit meet at -40?
Setting C = F in F = 1.8C + 32: C = 1.8C + 32, -0.8C = 32, C = -40. So -40 °C = -40 °F. It is the only point where both scales show the same number.
What is normal body temperature in both scales?
37 °C = 98.6 °F. Modern research suggests average is slightly lower (~36.7 °C / 98.2 °F), but 98.6 °F remains the traditional reference.
How hot is 100 °F in Celsius?
100 °F equals about 37.8 °C, feverish for humans, a warm summer day in most climates.
Do I use 1.8 or 9/5 in the formula?
They are identical: 9/5 = 1.8. Use whichever is easier to remember. The calculator uses the exact decimal.
All conversion runs in your browser. Nothing is uploaded. Celsius, Fahrenheit and Kelvin describe the same temperature in different scales.