Unlike length or weight, temperature scales start at different "zero" points. Celsius sets 0° at freezing water, while Kelvin sets 0 at "Absolute Zero"—the point where all atomic motion stops. Fahrenheit, primarily used in the US, sets the freezing point of water at 32°F and the boiling point at 212°F.
Scale Comparison
Kelvin
K
373 K
273 K
0 K
Celsius
°C
100°
0°
-273°
Fahrenheit
°F
212°
32°
-460°
Scales align at different points. Kelvin is shifted so 0 is Absolute Zero.
Kelvin Conversion Formulas
Scientists and engineers often need to convert Kelvin to "Degrees" (Celsius or Fahrenheit). Note that Kelvin is never referred to as "degrees," just "Kelvin" (e.g., 300 K).
Kelvin to Celsius (°C)
°C = K - 273.15
Simply subtract 273.15.
Kelvin to Fahrenheit (°F)
°F = (K - 273.15) × 1.8 + 32
Convert to Celsius first, then multiply by 1.8 and add 32.
Common Temperature Points
| Event | Kelvin | Celsius | Fahrenheit |
|---|---|---|---|
| Absolute Zero | 0 K | -273.15°C | -459.67°F |
| Water Freezes | 273.15 K | 0°C | 32°F |
| Human Body | 310.15 K | 37°C | 98.6°F |
| Water Boils | 373.15 K | 100°C | 212°F |
Frequently Asked Questions
- How do I convert Celsius to Fahrenheit?
- Multiply the Celsius temperature by 9/5 (or 1.8) and then add 32. The formula is: °F = (°C × 1.8) + 32.
- What is the difference between Celsius and Kelvin?
- The step size for both scales is exactly the same (an increase of 1°C is the exact same as an increase of 1 K). The only difference is the starting point: 0°C is the freezing point of water, whereas 0 K is absolute physical zero (-273.15°C).