Poise-Stokes Converter. Convert between dynamic viscosity and kinematic viscosity using this Poise-Stokes Converter. Enter the dynamic viscosity (η) in poise or centipoise and the fluid density (ρ) to get the kinematic viscosity (ν) in stokes or centistokes — or work in reverse. The tool applies the formula ν = η / ρ so you can switch between viscosity types for any fluid. Also try the Pipe Flow Calculator.
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. See also our use the Water Viscosity Calculator.
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. You might also find our calculate Primary Result, Flow Rate (Q) & Pressure Drop (ΔP) — Poiseuille's Law useful.