Temperature Calculator
Convert temperatures between Celsius, Fahrenheit, Kelvin, Rankine and Réaumur. Edit any unit and the rest follow. Temperature scales have different zero points, so the conversion adds an offset as well as scaling (°F = °C × 9/5 + 32). Every factor here is exact, so 32 °F shows exactly 0 °C.
About this tool
What does the Temperature Calculator do?
It converts a temperature into five scales: Celsius (°C), Fahrenheit (°F), Kelvin (K), Rankine (°R) and Réaumur (°Ré). Type in whichever scale you have and read the rest; nothing leaves your browser.
How to use
- Type a value in a row, e.g. 100 in Celsius. The other rows show 212 °F, 373.15 K, 671.67 °R and 80 °Ré.
- Set rounding digits for the number of decimals displayed.
- Turn on Description to see each scale's definition, and Ratio to see what 1 degree of each scale is in the top row's scale.
- Drag the handle at the left of a row to reorder scales; the top row is the (base unit).
- Press Up / Down in a row to add or subtract 1 degree of that scale.
Formulas
| From °C to | Formula |
|---|---|
| Fahrenheit | °F = °C × 9/5 + 32 |
| Kelvin | K = °C + 273.15 |
| Rankine | °R = (°C + 273.15) × 9/5 |
| Réaumur | °Ré = °C × 4/5 |
Reference points
| °C | °F | K | |
|---|---|---|---|
| Absolute zero | −273.15 | −459.67 | 0 |
| Water freezes | 0 | 32 | 273.15 |
| Body temperature | 37 | 98.6 | 310.15 |
| Water boils (1 atm) | 100 | 212 | 373.15 |
| −40 is the same | −40 | −40 | 233.15 |
Features
- Five temperature scales with exact factors and offsets
- Edit any row to convert in both directions
- Rounding control, thousands separators, ratios and descriptions
- Scale order, value and options are remembered locally
FAQ
Why does the Ratio show 1 °C = 33.8 °F and not 1.8?
The ratio converts the temperature 1 °C, which is 33.8 °F. A temperature difference of 1 °C is 1.8 °F; use the Up / Down keys to step by one degree.
Can I enter a temperature below absolute zero?
The calculator accepts it, but no physical temperature is below 0 K (−273.15 °C, −459.67 °F).
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