What is the standard SI unit for temperature?

The story behind the answer

The SI base unit for thermodynamic temperature is the kelvin (K). The Kelvin scale starts at absolute zero—the lowest possible temperature where thermal motion is minimal—so 0 K equals −273.15 °C. Its increments are the same size as Celsius, but Kelvin has no degree symbol and is used in scientific measurements.

Named after Lord Kelvin, it’s the only SI base unit named after a person; write the unit name in lowercase (kelvin) with the symbol K. Memory tip: “Kelvin = absolute,” since it’s anchored to absolute zero. Rankine is an absolute scale tied to Fahrenheit, and Celsius/Fahrenheit are everyday scales, but only kelvin is the SI standard.