What is the formula for Celsius to Kelvin?

K = °C + 273.15. The Kelvin scale starts at absolute zero (−273.15 °C), so every Celsius value maps to a Kelvin value by adding exactly 273.15.

What is absolute zero in Celsius?

Absolute zero is −273.15 °C, which equals 0 K. It is the lowest theoretically possible temperature — the point where all molecular thermal motion ceases.

Why does science use Kelvin instead of Celsius?

Kelvin is an absolute scale with no negative values, which makes equations like the ideal gas law, Wien's displacement law, and Boltzmann's equation work correctly. Negative temperatures would produce physically nonsensical results in those formulas.

What is the boiling point of water in Kelvin?

373.15 K (100 °C at standard atmospheric pressure). The freezing point is 273.15 K (0 °C).

Can Kelvin be negative?

No. Zero kelvin (absolute zero) is the lowest possible temperature. Kelvin values are always zero or positive, which is one reason scientists prefer this scale for thermodynamic calculations.

Celsius to Kelvin Converter

Convert any Celsius temperature to Kelvin instantly, with absolute zero context and scientific reference points.

Enter Temperature

Celsius (°C)

Quick presets

Result

Kelvin (K)

373.15 K

Context

Distance from absolute zero 373.15 K

Formula used K = °C + 273.15

Common Temperature Reference Points

Reference	°C	K
Absolute zero	−273.15	0.00
Liquid nitrogen (boiling)	−196.00	77.15
Water freezes (0 °C)	0.00	273.15
Room temperature (~20 °C)	20.00	293.15
Human body temperature	37.00	310.15
Water boils (100 °C)	100.00	373.15

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Summary

Convert any Celsius temperature to Kelvin instantly, with absolute zero context and scientific reference points.

How it works

Enter any Celsius temperature in the input field.
The tool applies the formula K = °C + 273.15 in real time.
The Kelvin result and its distance from absolute zero are displayed immediately.
Common reference temperatures are listed alongside for context.
Click "Copy" to copy the Kelvin value to your clipboard.

Use cases

Converting lab temperature readings from Celsius to Kelvin for scientific reports.
Understanding absolute temperature in thermodynamics and physics coursework.
Checking how far a cryogenic coolant temperature is from absolute zero.
Quick reference when working with the ideal gas law (PV = nRT).
Verifying temperature unit conversions in chemistry or astrophysics problems.
Teaching students the relationship between Celsius and Kelvin scales.

Frequently Asked Questions

Last updated: 2026-09-22 · Reviewed by Nham Vu