Convert Dynamic and Kinematic Viscosity Units

Convert dynamic and kinematic viscosity units

Dynamic (absolute) viscosity measures internal fluid friction in pascal-seconds (Pa·s), poise (P), or centipoise (cP). Kinematic viscosity is dynamic viscosity divided by density, reported in m²/s, stokes (St), or centistokes (cSt). They are not interchangeable without density because ν = η / ρ.

When to use this converter

Translate lab readings between SI (Pa·s) and cP common in lubricants.
Compare CFD inputs that expect m²/s with datasheet values in cSt.
Estimate kinematic viscosity from dynamic η and fluid density in kg/m³.

For temperature-dependent water viscosity, see the Water Viscosity Calculator. For poise–stokes with explicit density steps, try the Poise to Stokes Converter.

Frequently Asked Questions

What is the difference between cP and cSt?

Centipoise (cP) is dynamic viscosity; centistokes (cSt) is kinematic viscosity. Converting between them requires dividing or multiplying by density in consistent SI units (kg/m³).

Is water always 1000 kg/m³?

Near room temperature, water is close to 1000 kg/m³, but density changes with temperature and dissolved solids. Enter the density that matches your process.

Does this tool upload my numbers?

No. Conversions run entirely in your browser; values are not sent to a server.

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Viscosity Converter