Which is the Standard International (SI) unit of temperature? Kelvin or Celsius
http://physics.nist.gov/cuu/Units/units.html
Celsius
The Standard International (SI) unit of temperature is the Kelvin. To understand why Kelvin is the SI unit of temperature, let's explain the difference between Kelvin and Celsius and how to convert between them.
The Celsius scale is based on the properties of water. It sets the boiling point of water at 100 degrees Celsius and the freezing point at 0 degrees Celsius at sea level. It is commonly used for everyday measurements of temperature.
The Kelvin scale, on the other hand, is an absolute temperature scale and is closely related to the Celsius scale. It starts from absolute zero, which is the theoretical lowest possible temperature where all molecular motion ceases. Absolute zero is equivalent to -273.15 degrees Celsius. The Kelvin scale does not use the degree symbol, so temperatures are expressed simply in kelvins.
To convert a temperature from Celsius to Kelvin, you simply add 273.15 to the Celsius value. For example, 25 degrees Celsius is equivalent to 298.15 kelvins. Conversely, to convert a temperature from Kelvin to Celsius, you subtract 273.15 from the Kelvin value.
The Kelvin scale is used in many scientific disciplines because it is an absolute scale and eliminates any ambiguity or bias that can occur with the Celsius scale. It provides a consistent and universal reference point for temperature measurements.