Poise to Stokes Converter

Dynamic vs Kinematic Viscosity

Dynamic viscosity (measured in poise) describes how much force is needed to move a fluid at a given rate. Kinematic viscosity (measured in stokes) describes how fast a fluid moves under an applied force. Both describe thickness, but they answer different engineering questions.

Conversion Formula

Kinematic and dynamic viscosity are linked through fluid density:

$$\nu = \frac{\eta}{\rho}$$

where $\nu$ is kinematic viscosity in stokes, $\eta$ is dynamic viscosity in poise, and $\rho$ is density in grams per cubic centimeter. To convert stokes back to poise, multiply kinematic viscosity by density.

In practice, centipoise (cP) and centistokes (cSt) are used more often than poise and stokes. One poise equals 100 centipoise, and one stoke equals 100 centistokes.

Frequently Asked Questions

What is one poise in SI units?

One poise equals 0.1 pascal-seconds (Pa·s). Water at 20°C has a dynamic viscosity of about 0.010016 poise, or roughly 1 centipoise.

Why do I need density to convert poise to stokes?

Kinematic viscosity removes the mass effect by dividing dynamic viscosity by density. Without density, the two quantities cannot be converted.

When is kinematic viscosity used?

It is common in pipe flow, fuel spray analysis, and open-channel hydraulics where gravity or pressure drives motion rather than applied shear force.

Does temperature affect the conversion?

Yes. Both viscosity and density change with temperature. Use values measured at the same temperature for accurate conversion.

What density should I use for water?

At 20°C, water density is about 0.9982 g/cm³ and dynamic viscosity is about 0.010016 poise, giving kinematic viscosity near 0.010034 stokes.

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Dynamic vs Kinematic Viscosity

Conversion Formula

Frequently Asked Questions

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