Convert 300 K to Celsius — What Is 300 Kelvin in Celsius?

The formula to convert Kelvin to Celsius is:

°C = K − 273.15

or the approximate version commonly used in chemistry and physics:

°C = K − 273

For 300 K: °C = 300 − 273.15 = 26.85°C

or approximately: °C = 300 − 273 = 27°C

The answer 26.85°C is the precise value, and 27°C is the rounded/approximate value used in most chemistry problems.

Kelvin (K):

• SI unit of temperature (used in scientific calculations)
• Starts at absolute zero: 0 K = −273.15°C (the coldest possible temperature)
• No negative values possible (0 K is the minimum)
• Used in gas laws (Boyle's Law, Charles's Law), thermodynamics, and kinetics

Celsius (°C):

• Based on water's properties: 0°C = freezing point, 100°C = boiling point of water (at 1 atm)
• Used in everyday temperature measurement
• Can have negative values (e.g., −10°C in winter)

Relationship: The Kelvin and Celsius scales differ only by a fixed offset of 273.15. The size of 1 degree is the same on both scales.

K = °C + 273.15 °C = K − 273.15

Kelvin is used in chemistry because many physical laws require an absolute temperature scale:

1. Ideal Gas Law: PV = nRT — T must be in Kelvin; at T = 0 K, volume would be zero
2. Charles's Law: V ∝ T — valid only when T is in Kelvin
3. Arrhenius equation: k = A·e^(−Ea/RT) — R = 8.314 J/mol·K; T must be in Kelvin
4. Gibbs free energy: ΔG = ΔH − TΔS — T in Kelvin
5. Absolute zero (0 K) represents no thermal energy — cannot go below this

Using Celsius in these equations would give wrong results because Celsius has an arbitrary zero point (freezing of water), not a true zero of energy.