Temperature conversions
Temperature converter between the four major temperature scales: Celsius (°C), Fahrenheit (°F), Kelvin (K) and Rankine (°R). Because temperature scales have different zero points, conversion is not a simple multiplication — each direction uses its own formula.
The metric temperature unit used in 195 countries — water freezes at 0 °C
The US weather and cooking unit — water freezes at 32 °F
The SI temperature unit — starts at absolute zero
US absolute temperature scale — Fahrenheit-sized degrees from absolute zero
Tips for temperature conversions
Water freezes at 0 °C = 32 °F = 273.15 K. Water boils at 100 °C = 212 °F = 373.15 K at standard pressure.
Kelvin is the SI unit with zero at absolute zero (coldest possible temperature). Unlike C and F, Kelvin values are never negative.
The quick mental conversion: °F ≈ 2 × °C + 30. At 20 °C this gives 70 °F (actual: 68 °F — close enough for daily weather).
Human body core temperature: 37.0 °C = 98.6 °F. Fever starts at 38.0 °C = 100.4 °F.
Common mistakes to avoid
Forgetting that temperature conversion is not just multiplication — the offset (273.15 for K, 32 for F) matters.
Confusing degrees Celsius (°C) with degrees of temperature change. A rise of 5 °C equals a rise of 9 °F.
Reading a US weather forecast as Celsius — 90 °F is warm (32 °C), not freezing.
Using Kelvin below zero — absolute zero (0 K) is the minimum, there is no negative Kelvin.
Learn about each unit
Full encyclopedia page for every temperature unit — definition, history, uses, tips.