Temperature Converter
This temperature converter allows you to quickly convert between different temperature scales including Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur. Temperature is a physical property that quantitatively expresses hot and cold, and is one of the most commonly measured variables across science, medicine, industry, and daily life.
Temperature Measurement Systems
Celsius (°C)
The Celsius scale is part of the metric system and is used in most countries worldwide. On this scale, water freezes at 0°C and boils at 100°C at standard atmospheric pressure.
- Also known as centigrade
- Developed by Anders Celsius in 1742
- Standard unit in the International System of Units (SI)
Fahrenheit (°F)
The Fahrenheit scale is primarily used in the United States and its territories. On this scale, water freezes at 32°F and boils at 212°F at standard atmospheric pressure.
- Developed by Daniel Gabriel Fahrenheit in 1724
- Normal human body temperature is approximately 98.6°F
- Still used in everyday temperature measurements in the US
Kelvin (K)
The Kelvin scale is the base unit of temperature in the International System of Units (SI). It's an absolute temperature scale, meaning 0 K is absolute zero, the theoretical absence of all thermal energy.
- Proposed by William Thomson, 1st Baron Kelvin, in 1848
- No degrees symbol is used (K, not °K)
- Used extensively in scientific work
- Water freezes at 273.15 K and boils at 373.15 K
Rankine (°R)
The Rankine scale is an absolute temperature scale that uses the Fahrenheit degree. Zero on the Rankine scale is absolute zero.
- Proposed by William John Macquorn Rankine in 1859
- Used primarily in engineering systems in the US
- Water freezes at 491.67°R and boils at 671.67°R
Réaumur (°Ré or °r)
The Réaumur scale is a temperature scale where the freezing point of water is 0 degrees and the boiling point is 80 degrees.
- Developed by René Antoine Ferchault de Réaumur in 1730
- Historically used in Europe, particularly in France, Germany, and Russia
- Largely replaced by Celsius in the 20th century
Common Temperature Conversions
| From | To | Formula |
|---|---|---|
| Celsius (°C) | Fahrenheit (°F) | °F = (°C × 9/5) + 32 |
| Fahrenheit (°F) | Celsius (°C) | °C = (°F - 32) × 5/9 |
| Celsius (°C) | Kelvin (K) | K = °C + 273.15 |
| Kelvin (K) | Celsius (°C) | °C = K - 273.15 |
| Fahrenheit (°F) | Kelvin (K) | K = (°F + 459.67) × 5/9 |
| Kelvin (K) | Fahrenheit (°F) | °F = (K × 9/5) - 459.67 |
| Fahrenheit (°F) | Rankine (°R) | °R = °F + 459.67 |
| Celsius (°C) | Réaumur (°r) | °r = °C × 4/5 |
| Réaumur (°r) | Celsius (°C) | °C = °r × 5/4 |
Key Temperature Points
| Event/State | Celsius (°C) | Fahrenheit (°F) | Kelvin (K) | Rankine (°R) | Réaumur (°r) |
|---|---|---|---|---|---|
| Absolute Zero | -273.15 | -459.67 | 0 | 0 | -218.52 |
| Freezing Point of Water | 0 | 32 | 273.15 | 491.67 | 0 |
| Room Temperature | 20-25 | 68-77 | 293.15-298.15 | 527.67-536.67 | 16-20 |
| Average Human Body Temperature | 37 | 98.6 | 310.15 | 558.27 | 29.6 |
| Boiling Point of Water | 100 | 212 | 373.15 | 671.67 | 80 |