Dynamic viscosity measures a fluid’s internal friction; kinematic viscosity divides it by density and governs how fast momentum spreads. Water at 20 °C is about 1 cP and 1 cSt.
How to use the Poise–Stokes Converter
- Convert from
- Dynamic viscosity η
- Kinematic viscosity ν
- Density ρ
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose the direction, enter the viscosity and the density.
Inputs explained
| Field | What to enter |
|---|---|
| Convert from | Choose one: Dynamic viscosity η, Kinematic viscosity ν |
| Dynamic viscosity η | Units: cP (mPa·s), P, Pa·s |
| Kinematic viscosity ν | Units: cSt (mm²/s), St, m²/s |
| Density ρ | Units: kg/m³, g/cm³, g/mL, lb/ft³, lb/in³ |
Example values
How the main result changes when Dynamic viscosity η changes and everything else stays at the example values above:
| Dynamic viscosity η (cP (mPa·s)) | Kinematic viscosity ν (cSt (mm²/s)) |
|---|---|
| 0.501 | 0.5019 |
| 0.7515 | 0.7529 |
| 1 | 1.0038 |
| 1.25 | 1.2548 |
| 1.5 | 1.5057 |
| 2 | 2.0076 |
Formula
ν = η / ρ (1 St = 10⁻⁴ m²/s, 1 P = 0.1 Pa·s)
Worked example
Inputs — Convert from: Dynamic viscosity η; Dynamic viscosity η: 1.002 cP (mPa·s); Density ρ: 998.2 kg/m³.
Results — Kinematic viscosity ν = 1.003807 cSt (mm²/s); Dynamic viscosity η = 1.002 cP (mPa·s).
Key terms
- Kinematic viscosity
- Dynamic viscosity divided by density.
Frequently asked questions
What is a poise?
0.1 Pa·s, named after Poiseuille.
What is a stokes?
1 cm²/s, named after George Stokes.
Is honey's kinematic viscosity high?
Yes – thousands of cSt.
Why can air have a higher ν than water?
Its density is far lower.