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Free Celsius to Fahrenheit Converter

Convert temperatures between Celsius and Fahrenheit. Type in either box for an instant result, and check the table for everyday reference points.

1 °C = 33.8 °F

Pick any units and edit either box — it converts instantly in your browser.

Quick answer

To convert Celsius to Fahrenheit, multiply by 9/5 (1.8) and add 32: °F = °C × 9/5 + 32. For example, 20 °C = 68 °F. To convert Fahrenheit to Celsius, subtract 32 first, then multiply by 5/9.

Formula & method

Celsius to Fahrenheit

°F = °C × 9/5 + 32
  • °C — temperature in Celsius
  • 9/5 — 1.8, the ratio of a Fahrenheit to a Celsius degree
  • 32 — the freezing point of water in Fahrenheit

Fahrenheit to Celsius

°C = (°F − 32) × 5/9

Common Celsius to Fahrenheit

Celsius (°C)Fahrenheit (°F)
-40 °C-40.0 °F
-10 °C14.0 °F
0 °C32.0 °F
10 °C50.0 °F
20 °C68.0 °F
30 °C86.0 °F
37 °C98.6 °F
100 °C212.0 °F

Examples

Example 1: Freezing point of water
Input
0 °C
Result
32 °F
Why
0 × 9/5 + 32 = 32.
Example 2: Boiling point of water
Input
100 °C
Result
212 °F
Why
100 × 9/5 + 32 = 180 + 32 = 212.
Example 3: Body temperature
Input
37 °C
Result
98.6 °F
Why
37 × 9/5 + 32 = 66.6 + 32 = 98.6.

When to use this tool

  • Reading a weather forecast, oven setting, or thermostat in the other unit.
  • Converting a body temperature reading.
  • Following a recipe or instructions written for a different region.

Common mistakes

  • Adding 32 before multiplying. Multiply by 9/5 first, then add 32.
  • Using 2 instead of 1.8 for the ratio. The factor is 9/5 = 1.8 exactly.
  • Forgetting that −40 is the one temperature that reads the same in both scales.

Frequently asked questions

How do I convert Celsius to Fahrenheit?

Multiply the Celsius value by 9/5 (which is 1.8) and add 32. For example, 25 °C × 1.8 = 45, plus 32 = 77 °F.

How do I convert Fahrenheit to Celsius?

Subtract 32 from the Fahrenheit value, then multiply by 5/9. For example, (212 − 32) × 5/9 = 100 °C.

What is a quick mental estimate?

Double the Celsius value and add 30 for a rough Fahrenheit estimate. It’s close near room temperature but drifts at extremes.

At what temperature are Celsius and Fahrenheit equal?

At −40 degrees. −40 °C equals −40 °F — the only point where the two scales meet.

What is normal body temperature in each scale?

About 37 °C, which is 98.6 °F, though normal varies a little from person to person.

What temperature readings are the same in both Celsius and Fahrenheit?

Only −40 degrees. −40 °C = −40 °F — it's the unique point where the two scales intersect.

What is absolute zero in each scale?

Absolute zero (the theoretical lowest possible temperature) is 0 K (Kelvin), −273.15 °C, or −459.67 °F.

Sources & references

External references open in a new tab. We are independent and not affiliated with these organizations.

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