Last updated: November 18, 2025
Temperature conversion explained
Weather apps, lab notebooks, and engineering specs each prefer a different temperature scale. The Temperature Converter applies the standard affine relationships between Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur so you can translate any reading without re-deriving formulas.
How the conversion works
Celsius and Kelvin differ by an offset, while Fahrenheit and Rankine combine an offset and scale factor:
Plugging those into algebraic inverses lets you solve any direction exactly.
Units and conversions
| Scale | Zero point | Degree size |
|---|---|---|
| Kelvin (K) | Absolute zero | Same as °C |
| Celsius (°C) | Water freezes at 0 °C | Same as K |
| Fahrenheit (°F) | Water freezes at 32 °F | |
| Rankine (°R) | Absolute zero | Same step as °F |
| Réaumur (°Ré) | Water boils at 80 °Ré |
Worked examples
- Arctic forecast
Convert −35 °C to Fahrenheit and Kelvin.
Result: −31 °F (238 K).
- Body-temperature sensor
A thermistor reports 310 K. Express it in °C and °F.
Result: about 36.9 °C / 98.3 °F.
Tips and pitfalls
- Kelvin (and Rankine) never use degree symbols when spelled out; reserve “°” for Celsius, Fahrenheit, and Réaumur.
- Never subtract Fahrenheit readings before converting to Celsius—the scale has both an offset and a different degree size, so you must convert each value first when computing differences.
- Scientific calculations should take place in Kelvin so absolute zero is at 0 and proportional relationships stay linear.
- When mixing °C and Kelvin in the same spreadsheet, be explicit about which columns represent temperature vs. temperature differences; a 10 K temperature change equals a 10 °C change, but 10 K absolute is not 10 °C.