The temperature in Celsius degrees ($ t \; in \; ^ oC $)

Fusion of ice at sea level: ($ t \; = \; 0^oC $) Boiling point of water at normal pressure: ($t \;=\;100^oC$)

The absolute temperature in degrees Kelvin ($T \;in\; K$)

$T$=$t+273.15$

Fusion of ice at sea level: ($T \;=\;273.15 \;K$) Boiling point of water at normal pressure: ($T \;=\;373.15 \;K$)