Instantly convert between Celsius, Fahrenheit, Kelvin, Rankine & Delisle — with live formula breakdown, visual thermometer, and smart reference points.
Water boils at 100°C = 212°F
Water freezes at 0°C = 32°F
98.6°F = 37°C (body temp)
−40°F = −40°C (intersection)
0 K = absolute zero
−273.15°C = 0 K
273.15 K = 0°C
373.15 K = 100°C
0 °R = absolute zero
Used in thermodynamics
0 °De = boiling point
150 °De = freezing point
The formula to convert Celsius to Fahrenheit is: °F = (°C × 9/5) + 32. Water boils at 100°C = 212°F and freezes at 0°C = 32°F. Normal body temperature is 37°C = 98.6°F.
To convert Fahrenheit to Celsius: °C = (°F − 32) × 5/9. For example, 98.6°F = (98.6 − 32) × 5/9 = 37°C. The two scales intersect at −40° — the only point where °C and °F are equal.
Convert Celsius to Kelvin by adding 273.15: K = °C + 273.15. Absolute zero is 0 K = −273.15°C — the coldest possible temperature where all molecular motion stops.
The Kelvin scale is the SI base unit of thermodynamic temperature. It starts at absolute zero (0 K) and uses the same degree size as Celsius. Kelvin has no negative values and is used in science, physics, chemistry, and astronomy.
The Rankine scale is an absolute temperature scale based on Fahrenheit degrees. Absolute zero is 0 °R. Formula: °R = (°F + 459.67). It is used in some engineering disciplines in the United States, particularly in thermodynamics.
The Delisle scale is an inverted historical temperature scale invented by Joseph-Nicolas Delisle in 1732. Water boils at 0 °De and freezes at 150 °De. Formula: °De = (100 − °C) × 3/2. Absolute zero is 559.725 °De.
| Description | °C | °F | K |
|---|---|---|---|
| Absolute Zero | −273.15 | −459.67 | 0 |
| Water Freezes | 0 | 32 | 273.15 |
| Room Temperature | 20–22 | 68–72 | 293–295 |
| Human Body Temperature | 37 | 98.6 | 310.15 |
| Water Boils | 100 | 212 | 373.15 |
| Celsius = Fahrenheit | −40 | −40 | 233.15 |
| Oven (moderate) | 180 | 356 | 453.15 |
| Sun Surface | 5,505 | 9,941 | 5,778 |
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