About this tool
Temperature Converter
Temperature Converter moves between Fahrenheit, Celsius and Kelvin. Type into any of the three fields and the other two follow.
How to use it
- Type a value into whichever scale you have.
- Read the other two scales immediately.
The conversions
Celsius to Fahrenheit multiplies by 9/5 and adds 32. Fahrenheit to Celsius subtracts 32 first, then multiplies by 5/9. The subtraction has to come first because the two scales have different zero points as well as different degree sizes.
Kelvin is Celsius shifted so that zero is absolute zero, the point where molecular motion stops. Kelvin equals Celsius plus 273.15, and there are no negative Kelvin values.
Worked example
Three temperatures worth knowing:
- Water freezes0 C = 32 F = 273.15 K
- Water boils100 C = 212 F = 373.15 K
- The two scales meet-40 C = -40 F
Result: Minus 40 is the one temperature where Celsius and Fahrenheit give the same number.
When it helps
- Converting a recipe oven temperature between conventions.
- Reading a weather forecast from another country.
- Converting scientific data, which is usually in Celsius or Kelvin.
- Checking a fever reading against a scale you are unfamiliar with.
Common mistakes
- Multiplying before subtracting when going from Fahrenheit to Celsius. The 32 must come off first.
- Writing degrees Kelvin. Kelvin has no degree symbol, it is just kelvin.
- Converting a temperature difference the same way as a temperature. A change of 10 C is a change of 18 F, with no offset applied.
