My teachers (also the internet) tells me that Kelvin can never be negative. But when I converted $-275^\circ$C to Kelvin, it becomes $-1.85\,\rm K$. So, why everyone says that Kelvin can never be negative?


2 Answers 2


You've converted correctly, but the problem is that -275°C is colder than absolute zero, -273.15°C. Temperatures colder than this are not possible.

The conversion formula is just a maths formula, if you plug in a number it will spit out another number. The formula doesn't check that what you've entered is possible.

  • They tell you correctly that a Kelvin value can't be negative, $T>0 \,\mathrm K$.

  • Also, they should have told you that a degrees Celsius value can't be below $T>-273.15 \,^\circ\mathrm C$.

Sure, you can make up a number below this value, such as $-275\,^\circ \mathrm C$. Just like you can make up a number such as $-10\,\mathrm K$. These numbers just don't represent reality. A lower temperature limit is a feature of the world we live in. The above two values for the lower limit are identical - called absolute zero - just given in different unit systems.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.