Poise-Stokes Converter

Viscosity is measured in two ways. Dynamic (absolute) viscosity is measured in poise (P) or centipoise (cP) in the CGS system, and in pascal-seconds (Pa·s) in SI units. Kinematic viscosity is measured in stokes (St) or centistokes (cSt) in CGS, and in m²/s in SI units.

There is no fixed conversion between poise and stokes without knowing the fluid density, because they measure different things. The relationship is ν (St) = η (P) / ρ (g/cm³). For water at ~20°C with a density of ~1 g/cm³, 1 poise equals approximately 1 stokes.

Use the formula ν = η / ρ, where ν is kinematic viscosity in stokes, η is dynamic viscosity in poise, and ρ is density in g/cm³. Simply divide the poise value by the fluid's density in g/cm³ to get stokes.

Rearrange the formula to η = ν × ρ. Multiply the kinematic viscosity in stokes by the fluid's density in g/cm³ to obtain the dynamic viscosity in poise.

Kinematic viscosity is the ratio of dynamic (absolute) viscosity to fluid density. It describes how a fluid flows under gravity and is commonly used in applications like lubrication and fluid flow analysis. Its SI unit is m²/s, and the CGS unit is the stokes (St).

Dynamic viscosity (η) measures the internal resistance of a fluid to flow or shear stress — essentially how 'thick' it is. Kinematic viscosity (ν) accounts for the fluid's density and describes how quickly a fluid moves under gravity. Kinematic viscosity = dynamic viscosity / density.

Diesel has a density of approximately 0.85 g/cm³. Using η = ν × ρ: 0.025 St × 0.85 g/cm³ = 0.02125 poise, or about 2.125 centipoise (cP).

Use the formula η (cP) = ν (cSt) × ρ (g/cm³). Since 1 cP = 1 mPa·s and 1 cSt = 1 mm²/s, you can also write: η (in cP) = ρ (in kg/m³) × ν (in cSt) / 1000. Both expressions give the same result.