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Temperature Converter

Type a temperature and pick the scales. The line below the result shows where the two scales meet, which is more useful here than a conversion factor.

Result

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Why temperature is not like other units

Every other unit on this site converts by a factor: one metre is a fixed number of feet, and zero is zero in both. Temperature scales do not share a zero. Water freezes at 0 °C and 32 °F, so converting means shifting as well as stretching — the formula is °F = °C × 9/5 + 32.

This is the classic mistake in conversion tools: treat the ratio as a factor and 0 °C becomes 0 °F, when the answer is 32 °F. The two scales agree at exactly one point, −40°, which is why that number shows up in trivia.

Frequently asked questions

What is the formula for Celsius to Fahrenheit?

Multiply by 9/5 and add 32. So 20 °C is 20 × 1.8 + 32 = 68 °F. Going back, subtract 32 first, then multiply by 5/9.

At what temperature are Celsius and Fahrenheit the same?

At −40°. It is the only point where the two scales meet, because they run at different rates from different starting points and cross exactly once.

Why does Kelvin have no degree symbol?

Kelvin is an absolute scale, not a relative one — it starts at absolute zero rather than at an arbitrary reference like the freezing point of water. By convention it is written as "300 K", not "300 °K".

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