Temperature Converter

Convert temperatures between Celsius, Fahrenheit, Kelvin, and other temperature scales.

Temperature Converter

Convert temperatures between Celsius, Fahrenheit, and Kelvin. Unlike most unit conversions, temperature scales have different zero points, so the conversion uses an offset as well as a scale factor.

Conversion formulas

  • °F = °C × 9/5 + 32
  • °C = (°F − 32) × 5/9
  • K = °C + 273.15
  • °C = K − 273.15
  • °F = (K − 273.15) × 9/5 + 32

A few anchor points make sanity-checking easy: water freezes at 0 °C = 32 °F = 273.15 K, water boils at 100 °C = 212 °F at standard atmospheric pressure, normal body temperature is about 37 °C = 98.6 °F, and −40 °C = −40 °F is the point where the two scales meet.

Worked example

Convert a US oven setting of 350 °F to Celsius:

  • 350 − 32 = 318
  • 318 × 5/9 = 176.67

So 350 °F is about 177 °C, which is why many recipes round it to 180 °C in fan-off metric ovens.

Going the other way, a 22 °C room in Fahrenheit is 22 × 9/5 + 32 = 39.6 + 32 = 71.6, so 71.6 °F.

When to use this converter

  • Cooking: US recipes give oven temperatures in Fahrenheit, while ovens in most other countries are marked in Celsius.
  • Travel and weather: a forecast of 30 °C means a hot day (86 °F), which is easy to misjudge if you are used to the other scale.
  • Science and engineering: thermodynamic calculations use Kelvin, and lab protocols frequently need converting to the scale of the available equipment.
  • Home and health: thermostats, aquarium heaters, and fever thermometers are sold with either scale depending on the market.

Tips for accurate conversions

  • Temperature conversions are not simple multiplications. Doubling 10 °C to 20 °C does not double the Fahrenheit value, because the scales have different zero points.
  • Kelvin has no degree symbol: write 300 K, not 300 °K. Zero kelvin (−273.15 °C) is absolute zero, so negative kelvin values never appear in ordinary use.
  • Converting a temperature *difference* is different from converting a temperature *reading*. A change of 5 °C equals a change of 9 °F; the +32 offset only applies to actual readings.
  • When a recipe says 180 °C fan (convection), the conventional-oven equivalent is usually about 200 °C, or roughly 390 to 400 °F. The scale conversion will not account for fan versus conventional heat.
  • Some older sources use Rankine (°R = °F + 459.67) or Réaumur; this converter focuses on the three scales in everyday and scientific use.

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Other unit tools include the Length Converter, Pressure Converter, Energy Converter, and Data Storage Converter. For text, try the Word Counter.

Frequently asked questions

What is the formula to convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 and add 32: °F = °C × 9/5 + 32. For example, 20 °C is 68 °F. To convert the other way, subtract 32 from the Fahrenheit value and multiply by 5/9.
How do I convert Celsius to Kelvin?
Add 273.15: K = °C + 273.15, so 25 °C is 298.15 K. Kelvin is written without a degree symbol, and 0 K (absolute zero) equals −273.15 °C, so kelvin values are never negative in ordinary use.
At what temperature are Celsius and Fahrenheit equal?
At −40 degrees, since −40 × 9/5 + 32 = −40. It is the only point where the two scales read the same, and it makes a handy check that a converter is applying both the scale factor and the offset correctly.
Why can't I just multiply to convert temperatures?
Celsius and Fahrenheit have different zero points, so the conversion needs an offset (+32 or −32) as well as the 9/5 scale factor. Note that a temperature difference converts by the factor alone: a change of 5 °C equals a change of 9 °F, with no offset.
What is 350 °F in Celsius for baking?
350 °F is about 176.7 °C, which metric recipes usually round to 175 or 180 °C. Remember that fan (convection) ovens cook hotter than conventional ovens at the same setting, and the scale conversion does not account for that.
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