°C to K Converter
Convert Celsius temperatures into Kelvin values
Celsius to Kelvin FAQ
How do you convert Celsius to Kelvin exactly?
The exact relationship is very simple: K = °C + 273.15. Both scales use the same step size, so you do not need to multiply or divide, only shift the zero point. For example, 20 °C + 273.15 = 293.15 K. This calculator applies the °C to K formula directly, so you can focus on your physics, chemistry or climate calculations instead of doing the addition manually each time.
Why do we add 273.15 when converting to Kelvin?
The Celsius and Kelvin scales share the same degree size, but their zeros are different. The Kelvin scale starts at absolute zero, the coldest possible temperature, while 0 °C is the freezing point of water at standard pressure. By definition, the difference between these two points is exactly 273.15 degrees. That is why K = °C + 273.15 and °C = K − 273.15.
What is absolute zero in °C and K?
Absolute zero is the lowest possible temperature, where thermal motion in matter is at its minimum. It corresponds to:
- 0 K by definition
- −273.15 °C
The Kelvin scale is built so that absolute zero is at 0 K, which is why scientists and engineers prefer Kelvin for thermodynamic work.
When should I use Kelvin instead of Celsius?
Kelvin is the SI base unit of thermodynamic temperature and is required in many formulas in physics, chemistry and climate science. Ideal gas laws, blackbody radiation, reaction-rate equations and many engineering correlations expect temperature in Kelvin. Celsius is more convenient for everyday weather and comfort descriptions, but Kelvin is the right choice whenever absolute temperature appears inside equations.
Can I use this converter for lab reports and homework?
Yes. Many lab manuals and exam questions say “convert to Kelvin” before using a formula. This Celsius to Kelvin converter does exactly that step. Just be sure to follow any rounding rules your course, institution or journal gives, such as how many significant figures to report in your final answer.
How many decimal places of Kelvin do I need?
In a lot of lab and engineering contexts, two decimal places in Kelvin are enough, especially if your Celsius measurements are only precise to 0.1 °C or 0.01 °C. For example, 25.0 °C becomes 298.15 K, which you might reasonably report as 298.2 K depending on your rules. The calculator keeps full precision internally and then prints a clean, readable Kelvin value so you can round as needed.
What if my starting temperature is already in Kelvin?
If you already have Kelvin, you do not need this page: you can plug K directly into most physics and chemistry formulas. If you want to see the corresponding Celsius value, use °C = K − 273.15 or the dedicated K to °C converter. For more combinations, you can move between °C, °F and K using the full temperature conversion calculator.
From everyday Celsius readings to absolute Kelvin values
This °C to K converter is made for the moment when a temperature that feels familiar in Celsius suddenly needs to be used in an equation, simulation or data table in Kelvin. That is common in thermodynamics, reaction kinetics, material science, climate studies and many engineering disciplines. Instead of doing “+273.15” on a handheld calculator again and again, you type the Celsius value once and get a line like “20 °C = 293.15 K”.
1. Single Celsius input, single Kelvin result
The interface stays deliberately minimal: one input for °C and a result card underneath. You can enter everyday values like 0 °C or 25 °C, or much colder and hotter conditions used in lab and industry. The converter adds 273.15 exactly and presents the Kelvin result with sensible formatting that works on phones, tablets and desktop screens.
If you later need to go back from Kelvin to Celsius, the “Swap Units” button takes you straight to the K to °C page. The two tools are designed as a pair so that you can move between everyday Celsius descriptions and absolute Kelvin values in a single click.
2. Simple linear relationship between °C and K
Celsius and Kelvin are closely linked: they share the same degree size, so a temperature change of 1 °C is the same size as a change of 1 K. The only difference is where zero is set. Celsius uses the freezing point of water, while Kelvin uses absolute zero. This leads to the compact conversion pair K = °C + 273.15 and °C = K − 273.15. The converter applies this relationship exactly, matching scientific calculators, textbooks and standards.
When you need to move between several temperature units at once (for example Kelvin, Celsius, Fahrenheit and sometimes Rankine), the temperature conversion calculator gives you a wider hub that keeps all of those scales aligned in one place.
3. Common °C to K values at a glance
These sample conversions match what the calculator produces and help build a feel for what everyday Celsius temperatures look like on the Kelvin scale:
| Celsius (°C) | Kelvin (K) |
|---|---|
| −273.15 °C | 0 K (absolute zero) |
| −40 °C | 233.15 K |
| 0 °C | 273.15 K (water freezes) |
| 20 °C | 293.15 K (room temperature) |
| 25 °C | 298.15 K |
| 37 °C | 310.15 K (body temperature) |
| 50 °C | 323.15 K |
| 100 °C | 373.15 K (water boils) |
A fast mental shortcut is to add 273 instead of 273.15. For example, 25 °C → about 298 K. That is often close enough for rough checks. When you need the exact value for equations or documentation, this converter uses the full 273.15 offset behind the scenes so your results stay consistent.
4. Where the °C to K converter shines
You will most often reach for this tool in situations like:
- Physics and thermodynamics — preparing temperatures for gas laws, heat engines and statistical mechanics problems.
- Chemistry and reaction kinetics — converting Celsius lab readings into Kelvin for rate laws and equilibrium expressions.
- Climate and atmospheric science — working with temperature profiles and anomalies that rely on absolute scales.
- Engineering and process control — feeding Celsius measurements into models and simulations that demand Kelvin.
- Education and homework — double-checking hand conversions before you plug numbers into formulas or exams.
Because it follows the official, linear relationship between Celsius and Kelvin, you can return to this Celsius to Kelvin converter any time and get consistent, predictable results that fit both classroom work and real-world lab and engineering tasks.
References and further reading on Celsius and Kelvin
These references explain how the Celsius and Kelvin temperature scales are defined and used:
- Celsius — describes the Celsius scale, its history and connection to Kelvin.
- Kelvin — covers the Kelvin scale as the SI base unit of thermodynamic temperature.
- SI Units — Temperature (NIST) — provides official background on temperature units and the Kelvin/Celsius relationship.
For critical scientific, industrial or regulatory work, always follow your organisation’s official conversion and rounding procedures when moving between Celsius, Kelvin and other temperature units.