Temperature Converter

Convert between Celsius, Fahrenheit, Kelvin and Rankine in an instant. Free, accurate and private — every calculation runs right in your browser.

How to use the temperature converter

  1. Enter a temperature. Type the reading you want to convert into the Value box — negative numbers are fine.
  2. Pick your scales. Choose the scale to convert from and the scale to convert to, or press ⇄ to swap them.
  3. Read the result. The converted temperature appears instantly, and the table below shows the value on every supported scale at once.

About this tool

This free temperature converter changes readings between the everyday Celsius and Fahrenheit scales as well as the absolute Kelvin and Rankine scales used in science and engineering. Unlike simple ratio conversions, temperature needs offsets built into each formula: to go from Celsius to Fahrenheit you multiply by 9/5 and add 32 (°F = °C × 9/5 + 32), to reverse it you subtract 32 and multiply by 5/9, and Kelvin is simply Celsius plus 273.15. It is useful for cooking and oven settings, weather, travel, lab work and homework.

Because water freezes at 0 °C (32 °F, 273.15 K) and boils at 100 °C (212 °F) at sea level, these are handy reference points, and absolute zero — the coldest possible temperature — sits at 0 K, which is −273.15 °C or −459.67 °F. Every calculation is done locally in your browser with JavaScript, so nothing you type is uploaded or stored and the converter keeps working offline.

Frequently asked questions

How do I convert Celsius to Fahrenheit?

Multiply the Celsius value by 9/5 (that is, 1.8) and add 32. For example, 20 °C × 1.8 + 32 = 68 °F. To go the other way, subtract 32 from the Fahrenheit value and multiply by 5/9.

What is the difference between Kelvin and Celsius?

The two scales use the same size degree, but Kelvin starts at absolute zero. To convert, add 273.15 to a Celsius value to get Kelvin, or subtract 273.15 from Kelvin to get Celsius. Kelvin has no negative values.

At what temperature are Celsius and Fahrenheit equal?

They meet at −40 degrees: −40 °C is exactly −40 °F. It is the only point where the two scales give the same number.

Is my data sent anywhere?

No. The conversion runs entirely in your browser. Nothing you enter is transmitted to a server, so your data remains completely private.