Kelvin Converter

How to use the Kelvin converter

What this calculator does

This calculator converts one absolute temperature entered in kelvins into seven other temperature scales. It is useful for translating scientific, engineering, lighting, laboratory, and educational values into units that may be more familiar in a particular context. The conversion is an exact identity between scale definitions; it does not estimate sensor accuracy, heat flow, weather conditions, or material behavior. Kelvin is the SI base unit for thermodynamic temperature, as summarized by the BIPM guide to SI base units.

When to use it

Use the converter when reading a scientific paper that reports temperature in kelvins, comparing an LED color temperature with a Celsius or Fahrenheit reference, checking cryogenic or high-temperature calculations, or preparing coursework that requires several temperature scales from one starting value.

How to calculate

1. The calculator opens with a complete demonstration value of 293.15 K, so the results and the Excel workbook are ready immediately.
2. Replace the value in Temperature in Kelvin with any finite decimal at or above 0. Use a period for decimals, such as 310.15.
3. Read the live Celsius result first, then review Fahrenheit, Rankine, Delisle, Newton, Réaumur, and Rømer in the result cards and conversion table.
4. Select Download Excel to export the current typed input and all converted outputs to a validated .xlsx workbook.
5. Select Reset to clear the demonstration and all results. Export is then disabled until a complete valid Kelvin value is entered again.

Input guide

Temperature in Kelvin is the only required input. Enter a plain decimal number in kelvins, for example 293.15. The accepted domain begins at 0 K because the Kelvin scale is absolute; negative Kelvin values are rejected. Larger inputs increase every converted temperature monotonically, although offset scales can still display negative values at low Kelvin temperatures. Do not enter a degree symbol, unit letters, a decimal comma, or scientific notation. A common mistake is writing “20” when the intended value is 20 °C; that input means 20 K, which is – 253.15 °C.

Output guide

Temperature in Celsius is the primary output and equals kelvin minus 273.15. Temperature in Fahrenheit applies both a scale factor and an offset. Temperature in Rankine is another absolute scale and equals kelvin multiplied by 1.8. Temperature in Delisle decreases as Kelvin rises because its historical direction is reversed. Temperature in Newton, Temperature in Réaumur, and Temperature in Rømer are historical scales shown for comparison. The summary pills repeat Celsius, Fahrenheit, and Rankine for quick scanning. The conversion table lists the same canonical values with each scale name, symbol, and converted temperature. Negative values in offset scales are valid; 0 K is the lower physical boundary, not 0 °C or 0 °F.

Worked example

With the startup value 293.15 K, Celsius is calculated as 293.15 – 273.15 = 20.00 °C. Fahrenheit is 1.8 × 293.15 – 459.67 = 68.00 °F. Rankine is 1.8 × 293.15 = 527.67 °R. The remaining first-open values are 120.00 °De, 6.60 °N, 16.00 °Ré, and 18.00 °Rø. These exact values appear in the result cards, table, and downloadable workbook.

Learn more

NIST explains why the kelvin is an absolute scale and why the unit symbol is written K without a degree sign in its introduction to the kelvin. For broader measurement guidance, see NIST's SI temperature unit guidance.