Temperature Converter
Easily convert between different temperature units including Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur.
Temperature Scales Explained
Temperature measurement is essential in science, cooking, weather forecasting, and many other fields. Different temperature scales are used around the world, each with its own reference points and intervals.
Common Temperature Scales
| Scale | Symbol | Freezing Point of Water | Boiling Point of Water | Common Usage |
|---|---|---|---|---|
| Celsius | °C | 0°C | 100°C | Scientific, most countries worldwide |
| Fahrenheit | °F | 32°F | 212°F | USA, Belize, Cayman Islands, Palau |
| Kelvin | K | 273.15K | 373.15K | Scientific, absolute temperature |
| Rankine | °R | 491.67°R | 671.67°R | Engineering, thermodynamics (US) |
| Réaumur | °Ré | 0°Ré | 80°Ré | Historical, rarely used today |
Temperature Conversion Formulas
| Conversion | Formula |
|---|---|
| Celsius to Fahrenheit | °F = (°C × 9/5) + 32 |
| Fahrenheit to Celsius | °C = (°F - 32) × 5/9 |
| Celsius to Kelvin | K = °C + 273.15 |
| Kelvin to Celsius | °C = K - 273.15 |
| Fahrenheit to Kelvin | K = (°F - 32) × 5/9 + 273.15 |
| Kelvin to Fahrenheit | °F = (K - 273.15) × 9/5 + 32 |
| Celsius to Rankine | °R = (°C + 273.15) × 9/5 |
| Celsius to Réaumur | °Ré = °C × 4/5 |
| Réaumur to Celsius | °C = °Ré × 5/4 |
Important Temperature Reference Points
- Absolute Zero: -273.15°C = -459.67°F = 0K = 0°R
- Water Freezing Point: 0°C = 32°F = 273.15K = 491.67°R = 0°Ré
- Human Body Temperature: ~37°C = ~98.6°F = ~310.15K
- Water Boiling Point: 100°C = 212°F = 373.15K = 671.67°R = 80°Ré
- Room Temperature: ~20-22°C = ~68-72°F
Historical Temperature Scales
Celsius (°C)
Created by Anders Celsius in 1742, the Celsius scale was originally reversed - with 0 as the boiling point and 100 as the freezing point of water. After Celsius's death, the scale was reversed to its present form. It's the standard unit in the International System of Units (SI).
Fahrenheit (°F)
Developed by Daniel Gabriel Fahrenheit in 1724, this scale sets the freezing point of water at 32°F and the boiling point at 212°F. Fahrenheit initially defined 0°F as the temperature of a mixture of ice, water, and ammonium chloride, and 96°F as the human body temperature.
Kelvin (K)
Introduced by William Thomson (Lord Kelvin) in 1848, the Kelvin scale is an absolute thermodynamic scale where absolute zero is 0K (−273.15°C). It uses the same increment as the Celsius scale but has no negative values. It's commonly used in scientific research.
Rankine (°R)
Proposed by William John Macquorn Rankine in 1859, the Rankine scale is to Fahrenheit what Kelvin is to Celsius - an absolute temperature scale. Zero on the Rankine scale is absolute zero, and a one-degree Rankine change is equal to a one-degree Fahrenheit change.