18 kelvin to Celsius
-255.15 °C
18 K = -255.15 °C.
Celsius
-255.15°C
18 K = -255.15 °C
In short
How many Celsius is 18 kelvin?
18 K = -255.15 °C. 1 kelvin = 1.000000 Celsius, then − 273.15, so the working is 18 × 1.000000 − 273.1500 = -255.15.
The working
The factor below is an exact definition rather than a measurement, so nothing is approximated in the arithmetic. The only rounding on this page happens where a number is displayed.
1 kelvin = 1.000000 Celsius, then − 273.15 18 × 1.000000 − 273.1500 = -255.15
How much precision do you need?
Each row is the same answer cut at a different number of decimals, with what that choice costs you. Pick the shortest row whose error is smaller than whatever you are measuring with.
| Rounded to | Answer (°C) | Off by |
|---|---|---|
| Whole number | -255 | +0.15000 |
| 1 decimal | -255.1 | +0.05000 |
| 2 decimals | -255.15 | −0.00000 |
Round trip: take -255.15 °C back the other way and you land on 18.0000 K — a drift of 0.0000 K. That gap is the rounding, not the conversion.
What 18 K looks like
20 K
Hydrogen boils at about 20.3 kelvin at standard pressure, which is why liquid hydrogen rocket fuel needs vacuum-jacketed tanks.
Frequently asked questions
What is 18 kelvin in Celsius?
18 kelvin is -255.15 Celsius. 1 kelvin = 1.000000 Celsius, then − 273.15, so the working is 18 × 1.000000 − 273.1500 = -255.15.
How accurate is -255.15 °C?
Rounding to -255.15 °C and converting straight back gives 18.0000 K, a drift of 0.0000 K from the 18 you started with. The factor itself is exact; every bit of that difference comes from the rounding, not the conversion.
Nearby values
Any value at all
Kelvin to Celsius Converter
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