Temperature is one of the most frequently converted physical quantities. You're travelling to the US and see 95°F — what is that in Celsius? You're reading a scientific paper that lists values in Kelvin? Or you want to know where the two everyday scales meet? Everything is explained below.
The Three Main Temperature Scales
Celsius (°C)
The most widely used scale in everyday life — in Poland, Europe and most of the world. The zero point (0°C) is the freezing point of water, and 100°C is its boiling point at standard atmospheric pressure (1 atm). Proposed by Swedish astronomer Anders Celsius in 1742.
Fahrenheit (°F)
Used primarily in the United States, as well as the Bahamas, Cayman Islands and a few other territories. Water freezes at 32°F and boils at 212°F. Developed by Daniel Gabriel Fahrenheit in 1724.
Kelvin (K)
The scientific thermodynamic scale, where zero (0 K, or absolute zero) is the lowest theoretically possible temperature in the universe — approximately −273.15°C. One kelvin equals one degree Celsius in terms of increment size. Widely used in physics, chemistry and astronomy.
Conversion Formulas
Celsius ↔ Fahrenheit
- °F = °C × 9/5 + 32
- °C = (°F – 32) × 5/9
Examples:
- 20°C → 20 × 9/5 + 32 = 68°F (comfortable warm day)
- 98.6°F (body temperature) → (98.6 – 32) × 5/9 = 37°C
- 0°C → 32°F (water freezes)
- 100°C → 212°F (water boils)
Celsius ↔ Kelvin
- K = °C + 273.15
- °C = K – 273.15
Examples:
- 0°C → 273.15 K
- 100°C → 373.15 K
- 300 K → 26.85°C (a hot summer day)
Fahrenheit ↔ Kelvin
- K = (°F + 459.67) × 5/9
- °F = K × 9/5 – 459.67
The Meeting Point: −40°
There is one remarkable point where both everyday scales give the same reading: −40°C = −40°F. This is an extreme temperature encountered in places like Siberia or Antarctica.
Useful Reference Points
| Situation | Celsius (°C) | Fahrenheit (°F) | Kelvin (K) |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 20 | 68 | 293.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Water boils | 100 | 212 | 373.15 |
Convert Instantly Online
Rather than memorising formulas, use our online temperature converter — enter a value in any scale and the other two appear instantly.
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