Kelvin is the codename for a GPU microarchitecture developed by Nvidia, and released in 2001, as the successor to the Celsius microarchitecture. It was named with reference to William Thomson, 1st Baron Kelvin and used with the GeForce 3 and 4 series.

While Kelvin was not used as a marketing name at the time of the GeForce3's launch in 2001, the public name was first used by the nouveau Linux driver, and later on the Nvidia website.