Celsius to Kelvin

Free instant celsius to kelvin converter. K = °C + 273.15.

274.15
Formula
K = °C + 273.15

Common Celsius to Kelvin values

Celsius (°C)Kelvin (K)
-40233.15
0273.15
10283.15
20293.15
25298.15
37310.15
100373.15
10001273.15

How does Celsius to Kelvin conversion work?

Type a value in the Celsius (°C) field and the equivalent in Kelvin (K) appears instantly to the right. The math uses the exact formula shown above — no rounding errors, no approximations beyond standard floating-point precision. Use the swap button to flip the units and see the inverse conversion.

Celsius. The metric temperature unit. 0 °C is the freezing point of water; 100 °C is the boiling point at sea level.

Kelvin. The SI base unit for temperature, used in science. 0 K is absolute zero (−273.15 °C). No degree symbol — just "K".

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No submit button — the result updates as you type. Math runs entirely in your browser, so it’s as fast as your device.

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Works in any modern browser — Mac, Windows, Linux, iPhone, Android, tablets. No installation, no signup.

🎯 Accurate conversions

Conversion factors come from the official standard (NIST, BIPM, ISO definitions where applicable). Values are precise to standard floating-point limits.

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Free, every time. No account, no email, no “trial” that becomes paid. Ad-supported so you never have to pay.

Frequently asked

What is the formula for converting Celsius to Kelvin?+
The formula is: K = °C + 273.15. Type any value into the calculator above and the result appears instantly.
How do I convert Kelvin back to Celsius?+
Click the swap button (⇄) above to go to the Kelvin → Celsius converter, or use the inverse formula derived from the one shown.
Why does temperature conversion use offset, not just multiplication?+
Unlike most units, the zero point of Celsius and Fahrenheit are different (water freezes at 0 °C but 32 °F). That offset must be subtracted before — or added after — the multiplication. Kelvin shares the same scale as Celsius but starts at absolute zero (−273.15 °C).

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