Temperature Converter
How this temperature converter works
This converter instantly translates a temperature reading between Celsius, Fahrenheit, and Kelvin. Enter a value, pick the unit you are converting from, and the tool displays all three equivalent temperatures. The value matching your chosen input unit is highlighted, so you can focus on the other two converted results at a glance.
Conversion formulas
- Celsius → Fahrenheit: F = C × 9/5 + 32
- Celsius → Kelvin: K = C + 273.15
- Fahrenheit → Celsius: C = (F − 32) × 5/9
- Fahrenheit → Kelvin: K = (F − 32) × 5/9 + 273.15
- Kelvin → Celsius: C = K − 273.15
- Kelvin → Fahrenheit: F = (K − 273.15) × 9/5 + 32
The constant 273.15 is the offset between the Celsius scale (whose zero is the freezing point of water) and the Kelvin scale (whose zero is absolute zero). The 9/5 and 5/9 factors account for the different size of one degree on the Fahrenheit scale versus one degree on the Celsius/Kelvin scale: a change of 1°C equals a change of 1.8°F.
Common reference points
| Celsius | Fahrenheit | Kelvin | Reference |
|---|---|---|---|
| −273.15°C | −459.67°F | 0 K | Absolute zero |
| 0°C | 32°F | 273.15 K | Freezing point of water |
| 37°C | 98.6°F | 310.15 K | Human body temperature |
| 100°C | 212°F | 373.15 K | Boiling point of water |
Tips & notes
- Kelvin does not use the degree symbol — write 300 K, not 300°K.
- Temperatures below 0 K do not exist physically; this converter will not produce them.
- For everyday weather and cooking, Fahrenheit is common in the US while Celsius is used almost everywhere else.
- Scientific work generally uses Kelvin so that calculations involving energy and gas laws stay in absolute terms.
FAQ
How do I convert Celsius to Fahrenheit? Multiply the Celsius value by 9/5 and add 32: F = C × 9/5 + 32. So 25°C becomes 77°F.
What is Kelvin used for? Kelvin is the SI base unit of temperature used in science and engineering, starting at absolute zero (0 K) where molecular motion stops.
Why is 0 Kelvin absolute zero? Because 0 K is the lowest possible energy state of matter — all classical thermal motion stops, so no lower temperature can exist. This makes Kelvin an absolute thermodynamic scale rather than an arbitrary reference.