Kelvin to Celsius
Convert kelvin to celsius instantly — type a value and read the result, with the exact formula shown.
Example
0 K = -273.15 °C, 25 K = -248.15 °C, 100 K = -173.15 °C.
How it works
°C = K − 273.15. Every value is converted through a single kelvin base unit using internationally defined conversion factors, so any from/to pair stays consistent.
Good to know
Converting kelvin to celsius is an everyday task in physics, chemistry, astronomy, and engineering, where instruments and equations often report temperature on the absolute kelvin scale even though humans think in the more familiar celsius degrees. If you read a star's surface temperature as 5778 K, a cryogenics datasheet listing liquid nitrogen at 77 K, or a thermodynamics result in kelvin, shifting to celsius makes the number intuitive: 5778 K is about 5505 °C, and 77 K is a frigid −196 °C.
Both scales are metric and share the same degree size — a change of one kelvin is exactly the same as a change of one degree celsius. The difference is purely where each scale puts its zero. Celsius, devised in the 18th century, anchors 0 °C at the freezing point of water. Kelvin, the SI base unit for temperature, starts at absolute zero, the point where molecular motion stops, which sits 273.15 degrees below water's freezing point. That single offset is the whole story of the conversion.
The rule of thumb is simply subtract 273. For mental math you can round to subtracting 273 (or even 270 for a rough estimate) and add the missing 0.15 back only when you need precision. Because the degree spacing is identical, you never multiply or divide — there is no scaling factor, just the constant shift.
The most common mistake is using 273 instead of the exact 273.15, which quietly introduces a 0.15-degree error into every result; in lab work or calibration that rounding can matter. A second pitfall is forgetting that kelvin values are never written with a degree symbol — it is "300 K," not "300 °K" — and that kelvin cannot go negative, so any conversion producing a temperature below −273.15 °C signals a bad input rather than a real reading.
Frequently asked questions
How do you convert kelvin to celsius?
Use °C = K − 273.15. This tool applies that formula automatically as you type.
What is a quick reference for Kelvin to Celsius?
0 K = -273.15 °C; 25 K = -248.15 °C; 100 K = -173.15 °C.
Is this converter free and private?
Yes. It runs entirely in your browser, so your inputs never leave your device, there is no sign-up, and it works offline once loaded.
Are the conversions exact?
Conversions use internationally defined factors and are exact where the definitions are exact (for example, 1 inch = 2.54 cm). Displayed results are rounded for readability.
People also ask
What is 300 K in Celsius?
300 K equals 26.85 °C (300 − 273.15 = 26.85). That is close to a comfortable room temperature, which is why 300 K is often used as a round-number reference in science.
What is room temperature in Kelvin and Celsius?
Room temperature is usually taken as about 20–25 °C, which corresponds to roughly 293–298 K. The common scientific shorthand of 298 K equals 25 °C.
Why do you subtract 273.15 to convert Kelvin to Celsius?
Because the kelvin and celsius scales use the same size degree but different zero points. Kelvin starts at absolute zero, which is 273.15 degrees colder than the 0 °C freezing point of water, so subtracting 273.15 shifts kelvin onto the celsius scale.
What is absolute zero in Celsius?
Absolute zero is 0 K, which equals −273.15 °C. It is the lowest temperature physically possible, where molecular thermal motion is at a minimum.
Is a change of 1 Kelvin the same as 1 degree Celsius?
Yes. A temperature difference or change of 1 K is exactly equal to a change of 1 °C, because both scales have identical degree spacing. Only the starting zero point differs.
What is body temperature (310 K) in Celsius?
310 K equals 36.85 °C (310 − 273.15), which is approximately normal human body temperature of about 37 °C.
Do you write a degree symbol with Kelvin?
No. Kelvin is written as a plain number followed by K, such as 273 K, with no degree symbol. Only celsius and fahrenheit use the degree sign (°C, °F).
How do I quickly estimate Kelvin to Celsius in my head?
Subtract 273 from the kelvin value for a fast estimate, then subtract an extra 0.15 if you need the exact figure. For example, 500 K is roughly 227 °C, exactly 226.85 °C.
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