Poise to Stokes Converter — Viscosity Unit Conversion
Convert dynamic viscosity in Poise or cP to kinematic viscosity in Stokes or cSt — and vice versa — by dividing by the fluid density. Enter the viscosity value, its unit and the fluid density to get all equivalent values.
Dynamic viscosity unit
g/cm³
ν = η / ρ (centistokes = mm²/s)
- 1
Convert to Pa·s
1 cP × 0.001 = 0.001 - 2
Dynamic viscosity in Poise (P)
0.001 Pa·s ÷ 0.1 = 0.01 - 3
Kinematic viscosity (St)
0.01 P ÷ 1 g/cm³ = 0.01ν = η (P) / ρ (g/cm³) - 4
Kinematic viscosity (cSt)
0.01 St × 100 = 1
How does this calculator work?
Kinematic viscosity ν (St) = dynamic viscosity η (P) ÷ density ρ (g/cm³). Unit chain: 1 P = 0.1 Pa·s = 100 cP; 1 St = 1 cm²/s = 100 cSt = 10⁻⁴ m²/s. Water at 20 °C: η ≈ 1 cP, ν ≈ 1 cSt. You always need the density to switch between dynamic and kinematic.
Formula
How this is calculated
Viscosity measures a fluid's resistance to flow, but the term covers two related but distinct quantities. Dynamic (absolute) viscosity η describes the internal friction per unit velocity gradient and is measured in Poise (P) in CGS units or Pa·s (kg·m⁻¹·s⁻¹) in SI. One Poise equals 0.1 Pa·s; the common engineering unit centipoise (cP) equals 1 mPa·s. Water at 20 °C has η ≈ 1.002 cP; motor oils range from about 30 to 300 cP at operating temperature.
Kinematic viscosity ν is the dynamic viscosity divided by the fluid density: ν = η / ρ. In CGS units, η in Poise divided by ρ in g/cm³ gives ν in Stokes (St). One Stokes equals 1 cm²/s = 10⁻⁴ m²/s; the centistokes (cSt) is 10⁻² St and equals 1 mm²/s. Kinematic viscosity matters when gravity or inertia drives the flow — pipe flow, bearing lubrication and hydraulic-oil standards are all specified in cSt.
This converter assumes a constant density at the temperature of interest. Viscosity varies strongly with temperature; always use viscosity and density measured at the same temperature. The density of water at 20 °C is 0.998 g/cm³; petroleum oils are typically 0.84–0.92 g/cm³.
Frequently asked questions
Poise measures dynamic (absolute) viscosity — the fluid's internal resistance to shear. Stokes measures kinematic viscosity — that resistance divided by density. They are related by ν (St) = η (P) / ρ (g/cm³). You cannot convert between them without knowing the fluid density.
Water at 20 °C: ~1 cP (1 cSt). Honey: 2 000–10 000 cP. Engine oil SAE 30 at 40 °C: ~90–100 cSt. Diesel fuel: ~2–5 cSt at 40 °C. Air: ~0.018 cP (0.015 cSt). The cP and cSt values are numerically equal only when density = 1 g/cm³.
Many industrial applications — pipe flow, pump design, bearing lubrication — depend on how the fluid's own weight or inertia interacts with its viscosity, making kinematic viscosity (cSt) the natural choice. Chemical and process engineering often uses dynamic viscosity (cP) because it directly characterises shear stress.
Also known as
TG we-Calculate Editorial Team. (2026). Poise to Stokes Converter — Viscosity Unit Conversion [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/poise-stokes-converter
TG we-Calculate Editorial Team. "Poise to Stokes Converter — Viscosity Unit Conversion." TG we-Calculate. 2026. https://we-calculate.com/calculator/poise-stokes-converter.
TG we-Calculate Editorial Team, "Poise to Stokes Converter — Viscosity Unit Conversion," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/poise-stokes-converter
@misc{wecalculate_poise_stokes_converter, title = {Poise to Stokes Converter — Viscosity Unit Conversion}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/poise-stokes-converter}}, year = {2026}, note = {TG we-Calculate} }
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