Celsius vs Rankine
Side-by-side comparison, when-to-use-each guide, and instant conversion. Reviewed for 2026.
Everyday use everywhere outside the US. UK weather. Cooking. Body temperature.
US thermodynamics engineering, US refrigeration calculations, aerospace work using imperial units.
| Aspect | Celsius | Rankine |
|---|---|---|
| Zero point | Water freezing | Absolute zero |
| Boiling water | 100°C | 671.67 R |
| Absolute zero | -273.15°C | 0 R |
| Scale size | Same as Kelvin | Same as Fahrenheit |
| Used in | Worldwide everyday | US engineering only |
Frequently asked
Why does Rankine exist?
American engineers wanted an absolute-zero scale that worked with Fahrenheit temperatures, without converting through Celsius. William Rankine proposed it in 1859. It's almost extinct in normal use but persists in US thermodynamics textbooks.
Is Rankine ever used outside the US?
Almost never. International thermodynamics has standardised on Kelvin since 1968. Even British engineering switched in the 1960s. You'll only see Rankine in older US texts or specific US-built equipment.
Frequently asked questions
Why does Rankine exist?
American engineers wanted an absolute-zero scale that worked with Fahrenheit temperatures, without converting through Celsius. William Rankine proposed it in 1859. It's almost extinct in normal use but persists in US thermodynamics textbooks.
Is Rankine ever used outside the US?
Almost never. International thermodynamics has standardised on Kelvin since 1968. Even British engineering switched in the 1960s. You'll only see Rankine in older US texts or specific US-built equipment.