Celsius to Kelvin Calculator

Convert degrees Celsius to kelvin with the exact 273.15 offset, absolute-zero guardrails and a printable classroom, science or lab worksheet record.

Kelvin temperature25.00 °C + 273.15 = 298.1500 K · no uncertainty entered

Temperature°CMeasurement uncertainty± °CKelvin rounding incrementK

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Your numbers, formula and explanation together

Celsius to Kelvin Calculator: 298.15 K. 25.00 °C + 273.15 = 298.1500 K · no uncertainty entered

Formula applied

The exact method behind this answer

CalculationTime keeps the method visible so the number can be checked instead of blindly trusted.

Kelvin = degrees Celsius + 273.15. The size of one degree Celsius is the same as one kelvin, so a ± °C uncertainty carries across as the same ± K uncertainty.

Apply the formulaKelvin = degrees Celsius + 273.15. The size of one degree Celsius is the same as one kelvin, so a ± °C uncertainty carries across as the same ± K uncertainty.298.15 K25.00 °C + 273.15 = 298.1500 K · no uncertainty entered

Your live breakdown

Current inputs in the calculation

These values come from the controls above and update when the calculator changes.

Temperature: 25 °C
Measurement uncertainty: 0 ± °C
Kelvin rounding increment: 0.01 K

Resulting answer

298.15 K

25.00 °C + 273.15 = 298.1500 K · no uncertainty entered

Answer: 298.15 K
Live support: 25.00 °C + 273.15 = 298.1500 K · no uncertainty entered

Assumptions used

What this answer assumes

Best for science homework, thermodynamics worksheets, classroom demonstrations, lab notes and equipment readings where the absolute-temperature basis should stay visible.

The Celsius input is treated as thermodynamic temperature, not a temperature difference unless explicitly used that way in a classroom problem.
The calculator clamps values below −273.15 °C to absolute zero because ordinary thermodynamic temperature cannot go below 0 K.
The conversion offset is exact: 0 °C equals 273.15 K.
Measurement uncertainty is optional and is reported with the same numerical size in kelvin because Celsius and kelvin increments are equal.
For calibrated laboratory, safety, medical, food, industrial or compliance work, use the instrument certificate, required rounding rule and official procedure.

Master’s Tip

How to use the result well

Master’s Tip: use kelvin for thermodynamic temperature and Celsius for everyday weather or lab readings. Temperature differences have the same numerical size in °C and K, but absolute temperatures need the 273.15 offset.

Printable record

What belongs in the saved calculation

Save the inputs, result, formula, assumptions, page URL and date together so the calculation can be reviewed later.

Temperature: 25 °C
Measurement uncertainty: 0 ± °C
Kelvin rounding increment: 0.01 K

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Formula

Kelvin = degrees Celsius + 273.15. The size of one degree Celsius is the same as one kelvin, so a ± °C uncertainty carries across as the same ± K uncertainty.

Worked example

For 25 °C, kelvin = 25 + 273.15 = 298.15 K. If the thermometer uncertainty is ±0.2 °C, the converted record is 298.15 K ±0.2 K before any reporting-rounding policy is applied.

Professional note

Regional and unit assumptions

Standard or basis: SI temperature-scale conversion using the exact relation T/K = t/°C + 273.15. This is a measurement and worksheet calculator, not a calibration certificate or safety ruling.

Assumptions and limitations

The Celsius input is treated as thermodynamic temperature, not a temperature difference unless explicitly used that way in a classroom problem.
The calculator clamps values below −273.15 °C to absolute zero because ordinary thermodynamic temperature cannot go below 0 K.
The conversion offset is exact: 0 °C equals 273.15 K.
Measurement uncertainty is optional and is reported with the same numerical size in kelvin because Celsius and kelvin increments are equal.
For calibrated laboratory, safety, medical, food, industrial or compliance work, use the instrument certificate, required rounding rule and official procedure.

Methodology & Accuracy

How this calculator is checked

CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.

Formula used

Kelvin = degrees Celsius + 273.15. The size of one degree Celsius is the same as one kelvin, so a ± °C uncertainty carries across as the same ± K uncertainty.

Standard or basis

Standard or basis: SI temperature-scale conversion using the exact relation T/K = t/°C + 273.15. This is a measurement and worksheet calculator, not a calibration certificate or safety ruling.

Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.

Master's Tip

Questions

How do I convert Celsius to kelvin?

Add 273.15 to the Celsius temperature. For example, 25 °C + 273.15 = 298.15 K.

What is 0 °C in kelvin?

0 °C is exactly 273.15 K.

What is absolute zero in Celsius and kelvin?

Absolute zero is 0 K, which is −273.15 °C.

Is one degree Celsius the same size as one kelvin?

Yes. Celsius and kelvin have the same interval size; their zero points are different.

What should I print for a Celsius-to-kelvin worksheet?

Print the Celsius input, kelvin result, exact formula, rounding increment, uncertainty if used, date, page URL and notes area for the thermometer, classroom problem or lab source.

Calculation note

Celsius and kelvin use the same interval size but different zero points. Adding 273.15 moves a Celsius reading onto the absolute temperature scale used in SI science and thermodynamics.

Celsius is familiar; kelvin is absolute

Celsius is convenient for everyday and laboratory readings because it sits close to water-based reference points. Kelvin starts at absolute zero, which makes it the standard absolute-temperature scale for thermodynamic calculations.

The conversion is an offset, not a multiplier

Celsius-to-kelvin conversion adds 273.15. The interval size does not change, so a change of 1 °C is a change of 1 K, but an absolute temperature such as 25 °C must become 298.15 K.

Rounding should not invent precision

A converted temperature should keep the source measurement and uncertainty visible. Printing the formula, rounding increment and notes area helps prevent a neat kelvin answer from overstating the quality of the original reading.

Sources and further readingBIPM — The International System of Units (SI)NIST — SI Units: Temperature Encyclopaedia Britannica — Kelvin temperature scale