Popular conversions
1 pairsPascal-Second ↔ Centipoise
Pa·s ↔ cP
Unit guides
2 unitsDynamic Viscosity calculators
1 toolsDetailed guide to Dynamic Viscosity
Dynamic viscosity describes a fluid's internal resistance to flow — its 'thickness.' It is a key input for the Reynolds number and fluid-flow calculations.
The pascal-second is the SI unit of dynamic viscosity, while centipoise is the practical unit most often used in industry.
- Physical quantity
- Dynamic viscosity
- SI unit
- Pascal-second
- SI symbol
- Pa·s
- Water viscosity
- ≈ 0.001 Pa·s (1 cP) at 20 °C
- Typical use
- Reynolds number, lubricants and process fluids
Viscosity depends on conditions
Dynamic viscosity measures a fluid's resistance to shear. Pascal-seconds is the SI unit; poise and centipoise remain common in laboratory and industry references.
Viscosity can vary strongly with temperature and fluid composition. Do not compare values unless their temperature and the viscosity type—dynamic or kinematic—are stated.
What is dynamic viscosity?
Dynamic viscosity measures a fluid's resistance to shear, i.e. how hard it is to slide one layer of fluid past another.
High-viscosity fluids like honey flow slowly; low-viscosity fluids like water flow easily.
Pascal-second and centipoise
One pascal-second equals exactly 1,000 centipoise. Centipoise is preferred in industry because common liquids produce more readable numbers in that scale.
Water at 20 °C has a viscosity of about 1 centipoise (0.001 Pa·s), which is often used as a practical reference point.
Viscosity in the Reynolds number
The Reynolds number (Re = ρvD/μ) uses dynamic viscosity directly and determines whether a flow is laminar or turbulent — critical for pipe design and aerodynamics.
Dynamic viscosity should not be confused with kinematic viscosity (ν = μ/ρ), which factors in the fluid's density as well.
Unit comparison table
| Unit | Symbol | SI equivalent | System | Common use |
|---|---|---|---|---|
| Pascal-Second | Pa·s | SI reference unit | SI | Fluid mechanics and rheology |
| Centipoise | cP | 1 cP = 0.001 Pa·s | Practical viscosity unit | Oils, coatings and laboratory data |
Dynamic viscosity units
| Unit | Symbol | Information |
|---|---|---|
| Pascal-Second | Pa·s | View unit guide |
| Centipoise | cP | View unit guide |