MultiKit

Celsius to Fahrenheit Converter: °C to °F and Kelvin

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  • Version 1.0.3
  • Last updated 2026-11-02
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Type a temperature in degrees Celsius and see it in Fahrenheit and Kelvin. The formula is °F = °C × 9/5 + 32, so 25 °C is 77 °F.

Results keep 8 significant digits, or as many as the number you typed. US units (cup, gallon, fluid ounce) are the US definitions.

Everything you enter is processed in your browser and is never sent to a server.

How to use

  1. Type the temperature in °C. The first box has 25 as an example, and negative values such as -10 work.
  2. Read the equation at the top for °F. The table also shows Kelvin.
  3. To convert Fahrenheit to Celsius, choose Fahrenheit (°F) as the unit you typed and read the Celsius row.

Examples

0 °C
→ 32 °F
The freezing point of water.
37 °C
→ 98.6 °F
The usual body temperature.
100 °C
→ 212 °F
The boiling point of water at sea level.
-40 °C
→ -40 °F
The one temperature that is the same on both scales.
180 °C
→ 356 °F
A common oven setting for baking.
350 °F (choose Fahrenheit as the unit you typed)
→ 176.67 °C
An oven setting in American recipes. 350 − 32 = 318, times 5/9.
-273.15 °C
→ 0 K, or -459.67 °F
Absolute zero, the lowest temperature there can be.

How it works

This page is the unit converter with Celsius to Fahrenheit chosen. Conversions use the js-quantities library, which converts temperatures as points on a scale, not as differences, so that 0 °C is 32 °F and not 0 °F.

Why the formula has two steps

The two scales disagree about both the size of a degree and where zero is. Between the freezing and boiling points of water, Celsius counts 100 degrees and Fahrenheit counts 180 (from 32 to 212), so one Celsius degree is 9/5 of a Fahrenheit degree: that is the × 1.8. The zero points are also apart, water freezing at 0 on one and at 32 on the other: that is the + 32. Going back, undo the steps in the opposite order, subtracting 32 first and then multiplying by 5/9.

Temperatures you might look up

°C °F Use
-40 -40 The two scales meet
-10 14 A cold winter day
0 32 Water freezes
10 50 A cool day
20 68 Room temperature
30 86 A hot day
37 98.6 Usual body temperature
100 212 Water boils at sea level

For cooking, 180 °C is 356 °F, 200 °C is 392 °F and 220 °C is 428 °F. In the other direction, 350 °F is 176.67 °C, 400 °F is 204.44 °C and 450 °F is 232.22 °C, which recipes usually round to 175, 200 and 230. A fan or convection oven is commonly set lower than the recipe says, so follow your oven’s own instructions for that.

Mistakes to avoid

Adding 32 to a temperature difference gives a wrong answer, as the question above explains. Mixing up the order, 5/9 before the 32 is taken off, also happens: 68 °F is (68 − 32) × 5/9 = 20 °C, whereas 68 × 5/9 − 32 gives a nonsense figure.

Sources

Frequently asked questions

What is the formula for Celsius to Fahrenheit?
°F = °C × 9/5 + 32. Multiply by 1.8 and add 32. For 20 °C: 20 × 1.8 = 36, plus 32 is 68 °F.
What is the formula for Fahrenheit to Celsius?
°C = (°F − 32) × 5/9. For 68 °F: 36 × 5/9 = 20 °C.
Is there a quick way to estimate it in my head?
Double the Celsius figure and add 30. It is close in the range of everyday weather: 20 °C gives 70, against 68 °F exactly. It drifts as it gets hotter: 30 °C gives 90, against 86 °F, and 40 °C gives 110, against 104 °F.
Why do some countries use Fahrenheit?
It is the scale the United States and a few other places kept. Most of the world uses Celsius, and science uses Kelvin.
Is a 10 degree rise in Celsius a 10 degree rise in Fahrenheit?
No. A Fahrenheit degree is smaller, so a rise of 10 °C is a rise of 18 °F. The +32 in the formula only applies to a temperature on the scale, not to a difference. Warming from 20 °C to 30 °C is 18 °F more, which is 68 °F to 86 °F.
What is a fever in Fahrenheit?
38 °C is 100.4 °F, the figure often used as the point where a body temperature counts as a fever. 37 °C is 98.6 °F. Check what your doctor or thermometer says, because the cut-off varies with how and where it is measured.
How do I convert Celsius to Kelvin?
Add 273.15. 0 °C is 273.15 K and 25 °C is 298.15 K. A degree is the same size in both, so a rise of 1 °C is a rise of 1 K.
Does water always boil at 100 °C?
Only at standard sea-level pressure. The boiling point falls as the air pressure falls, so water boils at a lower temperature in the mountains.
Is anything sent to a server?
No. The conversion happens in your browser.

Guides

Version history
  • 1.0.3 — Adds why the formula has two steps, a table of everyday temperatures, oven settings, temperature differences versus temperatures, Kelvin, and how far the double-and-add-30 shortcut is off, with more examples and questions.
  • 1.0.2 — Clarifies the search title with the tool's main task and whether it is free or runs online.
  • 1.0.1 — Fixes a narrow screen keeping a label and its own field on the same line, instead of wrapping them apart.
  • 1.0.0 — First release.

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