Temperature Converter

It converts your value to Celsius first, then from Celsius to the scale you want. Each step uses the exact defined relationship between the scales: Fahrenheit is Celsius multiplied by 9/5 then shifted by 32, and Kelvin is Celsius shifted by 273.15. Because the scales start counting from different zero points, a temperature conversion is an affine transformation - a multiply and a shift - not a single ratio like converting metres to feet.

Fahrenheit = (Celsius x 9/5) + 32. For example, 20 degrees Celsius is (20 x 1.8) + 32 = 68 degrees Fahrenheit. To go the other way, Celsius = (Fahrenheit - 32) x 5/9, so 68 degrees Fahrenheit is (68 - 32) x 5/9 = 20 degrees Celsius.

Absolute zero - -273.15 degrees Celsius, -459.67 degrees Fahrenheit, or 0 kelvin - is the point at which a system has the minimum possible thermal energy. Nothing can be colder, so a temperature below it is not physically meaningful. This converter rejects any input that works out to less than absolute zero rather than returning a nonsense result.

A Celsius degree and a kelvin are exactly the same size, so a change of 1 degree Celsius is a change of 1 K. The difference is where each scale starts: Celsius puts 0 at the freezing point of water, while Kelvin puts 0 at absolute zero. That is why Kelvin never has negative values, and why you convert by simply adding or subtracting 273.15. Kelvin is the SI base unit of thermodynamic temperature.

Yes. Negative temperatures such as -40 degrees Celsius or -10 degrees Fahrenheit are completely valid and convert normally. The only value the converter refuses is one below absolute zero. Decimal inputs are fine, and results are shown to 4 decimal places.