Celsius to Fahrenheit
Convert Celsius to Fahrenheit — type a temperature in either box. The formula is °F = °C × 9/5 + 32.
How to use
- Enter a temperature in the Celsius field.
- The Fahrenheit value updates instantly.
- Negative values work exactly the same way.
- Check the reference table for the fixed points.
Celsius to Fahrenheit formula
Temperature is the one conversion that needs more than a multiplication: the scales disagree about where zero sits, so an offset is required as well as a ratio.
°F = °C × 9/5 + 32
Apply the offset first, then the ratio — reversing the order is the most common mistake.
Worked example
Converting 100 °C gives 212 °F.
100 °C → 212 °F
Reference points
Four temperatures worth memorizing, in both scales:
| Reference point | Celsius | Fahrenheit |
|---|---|---|
| water freezing | 0 °C | 32 °F |
| a mild room | 20 °C | 68 °F |
| body temperature | 37 °C | 98.6 °F |
| water boiling | 100 °C | 212 °F |
What is a degree Celsius?
Celsius is the everyday temperature scale in nearly every country, with 0 °C at water's freezing point and 100 °C at its boiling point.
Definition: Now defined from the kelvin: a temperature in °C equals the kelvin value minus exactly 273.15. Since 2019 the kelvin itself is fixed by the Boltzmann constant.
Where it is used: Weather forecasts, cooking, medicine and science worldwide outside the United States.
Worth knowing: A degree Celsius and a kelvin are the same size, so a temperature difference is numerically identical in both — only absolute readings differ.
What is a degree Fahrenheit?
Fahrenheit is the everyday temperature scale in the United States, with water freezing at 32 °F and boiling at 212 °F.
Definition: Defined against Celsius: °F = °C × 9/5 + 32. The 180-degree span between freezing and boiling gives it finer granularity than Celsius.
Where it is used: US weather, cooking, oven settings and body temperature.
Worth knowing: The two scales cross at −40°, where −40 °C and −40 °F are the same temperature.
Frequently asked questions
What is the formula to convert Celsius to Fahrenheit?
Use °F = °C × 9/5 + 32.
What is 0 °C in Fahrenheit?
0 °C is 32 °F.
What is 100 °C in Fahrenheit?
100 °C is 212 °F.
Does this work for negative temperatures?
Yes. The formula is linear, so it is valid above and below zero on either scale.
Is there anything to watch out for with celsius?
A degree Celsius and a kelvin are the same size, so a temperature difference is numerically identical in both — only absolute readings differ.
Is there anything to watch out for with fahrenheit?
The two scales cross at −40°, where −40 °C and −40 °F are the same temperature.