Operational Viscosity Calculator

 Kinematic viscosity at 40°C cSt
 Viscosity Index VI -
 Temperature T, viscosity v(T)  ºC
First the viscosity at 100°C is calculated using the viscosity at 40°C and the Viscosity Index. Calculation according ISO 2909 / ASTM D2270-226. Then the viscosity at temperature T is calculated with Ubbelohde-Walther equation according ASTM-D341.

A high VI-value indicates smaller viscosity changes with temperature. The VI of conventional mineral oils roughly ranges between 0 and 100, for modified mineral oils between 125 and 150, for synthetic esters between 140 and 160 and for silicone oils up to 200.