Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin and Rankine.
What the Temperature Converter does
Temperature scales differ in both their zero point and their degree size, so conversion needs an offset as well as a factor. Celsius and Fahrenheit meet at −40°, the one temperature where both scales read the same.
Formula
°F = °C × 9/5 + 32°C = (°F − 32) × 5/9K = °C + 273.15°R = (°C + 273.15) × 9/5
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Value | number | Yes | — |
| From | one of 4 options | Yes | — |
| To | one of 4 options | Yes | — |
How to use it
- Choose From and To.
- Enter Value.
- Select Calculate.
Worked example
Convert 100 °C to Fahrenheit.
- Value
- 100
- From
- Celsius
- To
- Fahrenheit
100 × 9/5 + 32 = 212 °F, the boiling point of water.
Reading the result
- Absolute zero is 0 K, −273.15°C or −459.67°F. Neither kelvin nor rankine takes negative values.
- The scales cross at −40°, the one temperature where Celsius and Fahrenheit read the same number.
Common mistakes
- Converting a temperature difference as though it were a temperature. A rise of 10°C is a rise of 18°F, not 50°F: differences use the ratio without the offset.
- Writing kelvin with a degree sign. It is 300 K, not 300°K.
Frequently asked questions
What is absolute zero?
−273.15 °C, or 0 K. It is the point where molecular motion reaches its minimum, and nothing can be colder.
When do Celsius and Fahrenheit agree?
At exactly −40 degrees. The two scales cross there.