How this calculator works
Dynamic viscosity measures the relation between shear stress and velocity gradient. Kinematic viscosity divides dynamic viscosity by mass density and describes momentum diffusivity. The selected unit applies to the corresponding numeric input; all six viscosity outputs are labelled explicitly. A density near 1000 kg/m3 makes the numerical cP and cSt values similar, but they are not interchangeable for other densities.
Formula
nu = mu/rho. 1 P = 0.1 Pa s; 1 cP = 0.001 Pa s. 1 St = 0.0001 m2/s; 1 cSt = 0.000001 m2/s. Therefore nu_cSt = mu_cP/rho_g/cm3.
Worked example
A liquid with dynamic viscosity 2 cP and density 800 kg/m3 has kinematic viscosity 2.5 cSt. At density 1000 kg/m3, the same 2 cP corresponds to 2 cSt.
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Frequently asked questions
Can poise be converted to stokes without density?
No. They describe different dimensions, and density is the required link.
Are cSt and mm2/s equivalent?
Yes. One centistoke equals one square millimetre per second exactly.
Does temperature matter?
Yes. Use viscosity and density measured at the same temperature and pressure.