Temperature Converter
Enter a temperature in Celsius, Fahrenheit or Kelvin and see it in all three units.
Celsius
20 °C
Fahrenheit
68 °F
Kelvin
293.15 K
°F = °C × 9 ÷ 5 + 32 = 20 × 9 ÷ 5 + 32 = 68
K = °C + 273.15 = 20 + 273.15 = 293.15
This tool is for information only. For sensitive work such as laboratory use, medicine storage or engineering, check the result yourself.
How to convert between temperature units
Celsius, Fahrenheit and Kelvin measure the same thing, but they start from different zero points and use different degree sizes. At sea-level pressure water freezes at 0 on the Celsius scale and 32 on Fahrenheit, and boils at 100 and 212. Kelvin uses the same degree size as Celsius but starts at absolute zero, and it is written without a degree sign.
°F = °C × 9 ÷ 5 + 32°C = (°F − 32) × 5 ÷ 9K = °C + 273.15°C = K − 273.15Worked example: for 20 °C, °F = 20 × 9 ÷ 5 + 32 = 68. In Kelvin it is 20 + 273.15 = 293.15 K.
Common temperatures at a glance
A handful of reference points covers most everyday conversions.
| Reference | Celsius | Fahrenheit | Kelvin |
|---|---|---|---|
| Absolute zero | -273.15 °C | -459.67 °F | 0 K |
| Where Celsius and Fahrenheit are equal | -40 °C | -40 °F | 233.15 K |
| Water freezes | 0 °C | 32 °F | 273.15 K |
| Room temperature | 20 °C | 68 °F | 293.15 K |
| Average body temperature (approximate) | 37 °C | 98.6 °F | 310.15 K |
| Water boils (at sea level) | 100 °C | 212 °F | 373.15 K |
Why Celsius and Fahrenheit meet at −40
The two scales give the same number at exactly one temperature: −40. Set °C equal to °F in the conversion formula and the solution is −40, so −40 °C and −40 °F are the same temperature.
When to use Kelvin
Kelvin is the SI unit of temperature and is used in physics, chemistry and engineering. 0 K is absolute zero, and no temperature can be lower. That is why this converter rejects anything below it.
A quick estimate in your head
To estimate Celsius from Fahrenheit, subtract 30 and halve. To estimate Fahrenheit from Celsius, double and add 30. The result can be a few degrees off: 20 °C gives 70 °F by this rule, while the exact value is 68 °F. Use the converter when you need the exact figure.