What Is Temperature Converter?

A free online temperature converter. Convert between Celsius (°C), Fahrenheit (°F), Kelvin (K), and Rankine (°R). Real-time conversion with the formula displayed for each conversion.

Temperature conversion is unique among unit conversions because the relationship between scales is linear but not proportional — different scales have different zero points and different interval sizes. Temperature Converter handles four scales — Celsius, Fahrenheit, Kelvin, and Rankine — displaying the conversion formula alongside each result so you can see exactly how the conversion works.

The converter presents four input fields, one for each scale. Enter a temperature in any field and the other three update instantly. For example, entering 25 in the Celsius field shows 77°F, 298.15 K, and 536.67°R. The conversion formula used for each conversion is displayed below the result, which is particularly useful for educational contexts and for understanding the mathematical relationship between scales.

Celsius is the standard unit in most countries and in scientific contexts, based on the freezing (0°C) and boiling (100°C) points of water at standard pressure. Fahrenheit is used primarily in the United States, with 32°F as the freezing point and 212°F as the boiling point of water. Kelvin is the SI base unit of temperature, starting at absolute zero (0 K = -273.15°C). Rankine is used in some engineering fields, particularly in the US, with the same interval size as Fahrenheit but starting at absolute zero.

Because temperature conversion involves both scaling and offset adjustment, the formulas are more complex than simple multiplication. Celsius to Fahrenheit requires multiplying by 9/5 and adding 32. Kelvin simply adds 273.15 to Celsius. The tool handles all the arithmetic, removing the mental math burden.