What are the exact formulas between °C, °F, K and °R?

K = °C + 273.15. °F = °C × 9/5 + 32. °R = K × 9/5. °C = (°F − 32) × 5/9. K = °R × 5/9.

Which temperature scales are absolute?

Kelvin (K) and Rankine (°R) are absolute temperature scales starting at absolute zero.

They are historically used in specific contexts. Including them ensures comprehensive conversion for archival, culinary, and historical documents.

Quick table (°C ↔ °F ↔ K)

°C	°F	K

Between °C, K, °F, °R:
- K = °C + 273.15
- °F = °C × 9/5 + 32
- °R = K × 9/5
- °C = (°F − 32) × 5/9
- K = °R × 5/9
Legacy scales (via °C):
- °Re = °C × 4/5
- °De = (100 − °C) × 3/2
- °N = °C × 33/100
- °Rø = °C × 21/40 + 7.5

The converter internally normalizes any input to Kelvin and then outputs all supported scales to avoid cumulative rounding error.

20 °C → K = 293.15, °F = 68, °R = 527.67, °Re = 16.

451 °F → °C = (451−32)×5/9 ≈ 232.78 → K ≈ 505.93.

Because Celsius and Kelvin have an exact offset of 273.15 between their zeros. We keep precision and let you round the display.

Rankine is common in some thermodynamics contexts (imperial system). It’s Kelvin scaled by 9/5 with the same absolute zero.