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Temperature converter

Switch between Celsius, Fahrenheit and Kelvin with the formula shown.

  • Runs in your browser
  • No sign-up

How to convert temperatures

  1. Enter the temperature.
  2. Choose the scale you have in From and the one you need in To: Celsius, Fahrenheit or Kelvin.
  3. Read the converted value, the formula used and the same temperature in all three scales.

The formulas

Temperature scales have different zero points, so you cannot convert by multiplying alone. The tool uses explicit formulas:

From To Formula
Celsius Fahrenheit °F = °C × 9/5 + 32
Fahrenheit Celsius °C = (°F − 32) × 5/9
Celsius Kelvin K = °C + 273.15
Fahrenheit Kelvin K = (°F − 32) × 5/9 + 273.15

Fahrenheit degrees are smaller than Celsius degrees. A change of 1 °C equals a change of 1.8 °F, which is why the formula multiplies by 9/5.

Worked example

A recipe asks for an oven at 180 °C. What is that in Fahrenheit and Kelvin?

  • Fahrenheit: 180 × 9/5 = 324, plus 32 gives 356 °F.
  • Kelvin: 180 + 273.15 = 453.15 K.

Ovens are marked in round steps, so 356 °F is set as 350 °F in practice, which is within 6 degrees.

Fixed points worth knowing

Event °C °F K
Absolute zero −273.15 −459.67 0
Water freezes 0 32 273.15
Normal body temperature 37 98.6 310.15
Water boils (sea level) 100 212 373.15

Checks the tool makes

If you enter a value below absolute zero, such as −300 °C, the tool tells you instead of returning a number that cannot exist. Numbers are shown with up to ten significant digits, so a conversion like 100 °F to Celsius reads 37.77777778.

Open Celsius to Fahrenheit or Fahrenheit to Celsius for a table of common values. For cooking amounts, the volume converter converts cups and milliliters, and the weight converter handles ounces and grams.

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Questions

How do I convert Celsius to Fahrenheit?

Multiply by 9/5 and add 32. 25 °C × 1.8 = 45, plus 32 is 77 °F.

How do I convert Fahrenheit to Celsius?

Subtract 32, then multiply by 5/9. For 98.6 °F: 66.6 × 5/9 = 37 °C.

What is absolute zero?

The lowest possible temperature: 0 K, −273.15 °C or −459.67 °F. The tool shows an error for anything colder.

At what temperature are Celsius and Fahrenheit equal?

At −40. The two scales cross there, so −40 °C is also −40 °F.

How do I convert Kelvin?

Kelvin steps are the same size as Celsius, so K = °C + 273.15. Water freezes at 273.15 K.

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