Celsius to Kelvin Converter
Convert Celsius to Kelvin for physics, chemistry, lab reports and engineering calculations. Add 273.15 — formula, reference table and worked examples included.
Last updated: May 2026
Why this conversion matters
Kelvin shows absolute temperature, so it appears in physics, chemistry and engineering much more often than general consumer tasks.
This page keeps the conversion direct and adds enough context to stop small mistakes in reports or homework.
Typical use cases
- physics and chemistry homework
- lab note checks
- sensor data comparisons
- engineering references
Quick reference
| °C | K |
|---|---|
| 0 | 273.15 |
| 25 | 298.15 |
| 100 | 373.15 |
| -40 | 233.15 |
Related tools and sections
Frequently Asked Questions
What is absolute zero in Kelvin?
Absolute zero is 0 K, equivalent to -273.15°C. It is the lowest possible temperature in the universe — a theoretical point where all molecular motion stops. Kelvin was designed so that absolute zero would be exactly 0, making it ideal for physics calculations.
Why is the 273.15 constant so important?
273.15 is the offset between the freezing point of water in Celsius (0°C = water freezes) and Kelvin (273.15 K = same freezing point). This constant is the direct conversion between the two scales and comes from defining absolute zero as 0 K.
When should I use Kelvin instead of Celsius?
Use Kelvin for physics, chemistry, and engineering calculations where you need an absolute temperature scale (not a relative one). Gas laws, thermodynamics, and radiation equations all expect Kelvin. Celsius is fine for everyday temperature references and cooking.