Viscosity-Temperature Calculator
Based on the Walther equation: given the kinematic viscosities V1 and V2 of a lubricant at temperatures T1 and T2, calculate the viscosity V3 at any temperature T3 (unit: mm²/s, i.e. cSt).
Instructions: ① Enter two temperature-viscosity reference points (the higher the temperature, the lower the viscosity should be); ② Enter the target temperature T3; ③ Click [Calculate] to get the corresponding viscosity.
cSt
cSt
Viscosity Index VI Calculation
Based on the ASTM D2270 standard piecewise formula, calculate the viscosity index VI from the kinematic viscosities at 40°C and 100°C, or inversely solve for the unknown viscosity at a specified VI.
Forward calculation: known 40°C / 100°C viscosity → find VI
cSt
cSt
Reverse calculation 1: known VI, 40°C viscosity → back-calculate 100°C viscosity
cSt
Reverse calculation 2: Given VI and 100℃ viscosity → back-calculate 40℃ viscosity
Tip: When VI ≥ 100, use ASTM D2270 Formula B for extrapolation; accuracy depends on the value range, and results are kept to 2 decimal places.
cSt
Blended Viscosity Calculator
Supports viscosity prediction for blends of two base oils in any proportion, as well as back-calculating the blend ratio from a target viscosity; the temperature coefficient K automatically adapts to 100℃ / 40℃ / -5℃ conditions.
A Given blend ratio → calculate blend viscosity
cSt
cSt
%
B Known target viscosity → Calculate blending ratio
cSt
cSt
cSt