Kelvin to Celsius Converter

Instant, two-way conversion across common engineering units.

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1 K = -272.15 °C(KelvinCelsius)

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Converting kelvin to Celsius

To convert kelvin to Celsius, subtract 273.15 from the value. Temperature scales use offsets as well as ratios, so a conversion formula is applied rather than a single multiplier.

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Equivalent temperature
373.15 K = 100 °C.
273.15 K = 0 °C.

Temperature scales have different zero points, so the values are matched at the same physical temperature rather than compared by size.

Kelvin (K)

The kelvin (K) is the SI base unit of thermodynamic temperature.

Origin
Defined by fixing the Boltzmann constant, with zero at absolute zero rather than a water reference.
Where it is used
Used in thermal calculations, U-value and heat transfer work, and all scientific reporting.
Relation to SI
K = °C + 273.15, and a change of 1 K equals a change of 1 °C.

Celsius (°C)

Celsius (°C) is the everyday temperature scale used in most of the world and in building physics.

Origin
Based on the freezing and boiling points of water at standard pressure, and now defined from the kelvin.
Where it is used
Used for design temperatures, thermal comfort, concrete curing and HVAC setpoints.
Relation to SI
0 °C = 273.15 K. A Celsius degree is the same size as a kelvin.

Frequently asked questions

How do I convert kelvin to Celsius?

To convert kelvin to Celsius, subtract 273.15 from the value. For example, 20 K equals -253.15 °C.

How do I convert back from Celsius to kelvin?

Reverse the formula: add 273.15 to the value. The converter above works in both directions, so you can type into either field.

Why does temperature conversion use formulas instead of ratios?

Celsius and Fahrenheit have different zero points, so a simple multiplier cannot work. Each conversion applies both a scale factor and an offset.

How do Celsius and Fahrenheit differ?

Water freezes at 0 °C or 32 °F and boils at 100 °C or 212 °F, so one Celsius degree covers 1.8 Fahrenheit degrees. The scales cross at -40.

When should I use kelvin?

Kelvin is the SI unit and starts at absolute zero, so it is used for thermal calculations, U-values and any scientific reporting. Temperature differences are identical in kelvin and Celsius.

Is this temperature converter free to use?

Yes. Every unit conversion runs in your browser, needs no account and is free for professional use.

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