Relative viscosity

Relative viscosity (${\displaystyle \eta _{rel}}$) (a synonym of "viscosity ratio") is the ratio of the viscosity of a solution (${\displaystyle \eta }$) to the viscosity of the solvent used (${\displaystyle \eta _{s}}$),

${\displaystyle \eta _{rel}={\frac {\eta }{\eta _{s}}}}$.

References

• IUPAC Compendium of Chemical Terminology