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Free Kelvin to Celsius Converter

Need to translate absolute temperature readings from Kelvin into familiar Celsius values? This converter handles the conversion instantly—perfect for astronomy, physics research, and understanding scientific data.

1 K = -272.15 °C

Pick any units and edit either box — it converts instantly in your browser.

Quick answer

To convert Kelvin to Celsius, subtract 273.15. This is the reverse of the Celsius-to-Kelvin conversion, translating absolute temperatures back into the more intuitive Celsius scale.

Formula & method

°C = K − 273.15

Temperature scales have an offset, so this is not a simple multiplication.

Kelvin to Celsius — common values

Kelvin (K)Celsius (°C)
0 K-273.15 °C
100 K-173.15 °C
200 K-73.15 °C
273.15 K0 °C
298.15 K25 °C
310.15 K37 °C
373.15 K100 °C
1,000 K726.85 °C

Examples

Example 1: Freezing point of water
Input
273.15 K
Result
0 °C
Why
The precise thermodynamic triple point definition used to calibrate scientific instruments.
Example 2: Standard laboratory temperature
Input
298.15 K
Result
25 °C
Why
Approximately 25°C; widely used as a reference condition in chemistry and material property measurements.
Example 3: Normal human body temperature
Input
310.15 K
Result
37 °C
Why
Approximately 37°C; the physiological set point maintained by the hypothalamus.
Example 4: Boiling point of water at sea level
Input
373.15 K
Result
100 °C
Why
Exactly 100°C; used as a calibration point for thermometers and thermal instruments.

Common mistakes

  • Treating temperature like a simple multiplication. Because the scales have an offset, you must add or subtract the constant — 0 °C is 32 °F, not 0 °F.
  • Converting in the wrong direction. This page goes Kelvin → Celsius; rearrange the formula to reverse it.

Frequently asked questions

When would I need to convert Kelvin to Celsius?

Kelvin is used in scientific instruments, data logs, and published research. When you read Kelvin values from a spectrometer, thermometer calibration, or astronomical observation, you might need to convert to Celsius for practical interpretation.

What happens if I convert a Kelvin value below 273.15?

Any Kelvin value below 273.15 would convert to a Celsius value below 0°C, representing sub-zero (frozen) conditions. However, you cannot have a Kelvin reading below 0 K—absolute zero is the theoretical minimum.

Why is Kelvin sometimes written as just K, not °K?

The SI (International System of Units) standard specifies that Kelvin should be written as K, not °K, because Kelvin is defined as an absolute scale. The degree symbol (°) is not used for absolute temperature units.

Is there rounding error in the 273.15 offset?

No. The value 273.15 is exact by definition—it's the difference between the absolute zero point and the freezing point of water. It is not a measured value subject to experimental error.

How are Kelvin temperatures measured in practice?

Modern Kelvin readings come from calibrated thermometers, thermocouples, infrared pyrometers, or resistance temperature detectors (RTDs). These instruments directly output in Kelvin for scientific work, then the values are often converted to Celsius for human interpretation.

What's the difference between Kelvin in physics vs. everyday measurement?

In physics and thermodynamics, Kelvin is mandatory for any calculation involving absolute temperature ratios (e.g., gas laws, entropy). In everyday life, Celsius and Fahrenheit are used because the offset doesn't affect relative temperature changes.

Sources & references

External references open in a new tab. We are independent and not affiliated with these organizations.

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