Temperature Converter: Units, Formulas, and Examples
Convert temperatures between Celsius, Fahrenheit, Kelvin, and Rankine.
How to convert temperature
°F = °C × 9/5 + 32; K = °C + 273.15; °R = K × 9/5.
Keep the source and target definitions consistent, apply the conversion to the original value, and round the final answer to the precision needed for your calculation.
Understanding temperature units
Temperature scales have different zero points as well as different degree sizes. This converter converts temperature readings rather than temperature differences. Kelvin and Rankine start at absolute zero.
Worked temperature examples
25 °C = 77 °F = 298.15 K = 536.67 °R. Water freezes at 0 °C or 32 °F at ordinary pressure.
Frequently asked questions
Which definitions should I use?
Values below absolute zero are rejected: −273.15 °C, −459.67 °F, 0 K, or 0 °R. Temperature differences use different formulas because offsets do not apply.
Why do displayed results sometimes differ slightly?
Intermediate arithmetic uses browser floating-point numbers. Display rounding and the precision of an original measurement can affect the last digits. The unit conversion does not improve the accuracy of a measured value.
Does converting back recover the original value?
Using the unrounded result normally recovers the original quantity within floating-point precision. Copying a rounded number can introduce a small difference.
How are the unit definitions documented?
For physical unit definitions and conversion factors, see the NIST conversion reference.