Celsius to Kelvin (°C to K) Converter
Use this Celsius to Kelvin converter to quickly convert °C to K with accurate results. Enter a temperature in Celsius, adjust your preferred decimal precision, and get the equivalent Kelvin value instantly.
This °C to K calculator uses the exact conversion formula of K = °C + 273.15, giving you precise results for chemistry, physics, thermodynamics, and all scientific temperature work.
Formula used: K = °C + 273.15
Need to convert Kelvin back to Celsius? Try our Kelvin to Celsius Converter.
Celsius to Kelvin Formula
To convert Celsius to Kelvin, simply add 273.15 to the Celsius value.
Formula:
K = °C + 273.15
For example, to convert 25°C to Kelvin, add 273.15.
25 + 273.15 = 298.15 K
So 25 degrees Celsius equals 298.15 Kelvin — approximately room temperature in scientific notation.
Key Temperature Benchmarks: °C to K
These reference points are essential for scientific work involving Celsius to Kelvin conversions:
- Absolute zero: -273.15°C = 0 K
- Water freezes: 0°C = 273.15 K
- Room temperature: 20°C = 293.15 K
- Body temperature: 37°C = 310.15 K
- Water boils: 100°C = 373.15 K
- Sun's surface: ~5500°C ≈ 5773 K
Celsius to Kelvin Conversion Table
Use this quick reference table for common °C to K conversions.
| Celsius (°C) | Kelvin (K) |
|---|---|
| -273.15°C | 0 K (absolute zero) |
| -100°C | 173.15 K |
| 0°C | 273.15 K |
| 20°C | 293.15 K |
| 37°C | 310.15 K |
| 100°C | 373.15 K |
| 200°C | 473.15 K |
| 500°C | 773.15 K |
| 1000°C | 1273.15 K |
| 5000°C | 5273.15 K |
Common Celsius to Kelvin Conversions
- 0°C to Kelvin: 0°C = 273.15 K (water's freezing point)
- 20°C to Kelvin: 20°C = 293.15 K (standard room temperature)
- 37°C to Kelvin: 37°C = 310.15 K (human body temperature)
- 100°C to Kelvin: 100°C = 373.15 K (water's boiling point)
- -273.15°C to Kelvin: -273.15°C = 0 K (absolute zero)
When to Convert Celsius to Kelvin
Kelvin is the official SI unit of temperature and is used whenever temperature must behave as an absolute quantity — not just a relative one. You'll need to convert Celsius to Kelvin for:
- Ideal gas law calculations (PV = nRT requires temperature in Kelvin)
- Thermodynamics problems involving heat engines, entropy, or enthalpy
- Blackbody radiation and Stefan-Boltzmann law calculations
- Chemistry equilibrium constants and Arrhenius equation work
- Astrophysics and astronomical temperature measurements
- Any physics formula where a proportional temperature relationship is required
Why Kelvin Cannot Be Negative
Unlike Celsius or Fahrenheit, Kelvin is an absolute scale — it begins at the coldest possible physical state. At 0 K (absolute zero, or -273.15°C), all molecular and atomic motion stops. There is no lower energy state, so there is no temperature below 0 K.
This is why using Celsius in science equations that rely on proportional temperature relationships gives wrong answers. A temperature of -10°C doesn't mean "negative energy" — but plugging a negative Celsius value into a formula that expects an absolute temperature produces physically meaningless results.
Converting to Kelvin first eliminates this problem entirely.
FAQ
How do I convert Celsius to Kelvin?
Add 273.15 to the Celsius value. The formula is K = °C + 273.15.
What is the formula for Celsius to Kelvin?
K = °C + 273.15. Kelvin and Celsius have equal-sized degrees — Kelvin just starts at absolute zero.
What is 0°C in Kelvin?
0°C equals 273.15 K — the freezing point of water.
What is 100°C in Kelvin?
100°C equals 373.15 K — the boiling point of water at standard pressure.
What is absolute zero in Celsius?
Absolute zero is -273.15°C, which corresponds to 0 K — the lowest possible temperature.
Can Kelvin be a negative number?
No. Kelvin starts at absolute zero (0 K). Negative Kelvin values are physically impossible.
Why is Kelvin used in science instead of Celsius?
Kelvin starts at absolute zero, making it proportional. Scientific laws like the ideal gas law require absolute temperature — using Celsius would produce incorrect results.