Viscosity - Dynamic Converter
Convert dynamic (absolute) viscosity between pascal-seconds, poise and centipoise.
Written by Rahman · Last reviewed
Quick answer
Dynamic viscosity measures a fluid's resistance to shear. The SI unit is the pascal second: one poise is 0.1 Pa·s and one centipoise is 0.001 Pa·s. Water at 20 °C is almost exactly 1 centipoise, which is why cP survives as the everyday working unit despite not being SI.
| Pascal second (Pa·s) | 1 |
| Millipascal second (mPa·s) | 1000 |
| Poise (P) | 10 |
| Centipoise (cP) | 1000 |
| Dyne second per cm² (dyn·s/cm²) | 10 |
| Pound-force second per ft² (lbf·s/ft²) | 0.02088543423 |
About the Viscosity - Dynamic Converter
Dynamic viscosity measures a fluid's internal resistance to flow: its "thickness". The SI unit is the pascal second, while the poise and centipoise are also widely used.
It is important in lubrication, pipeline design and the study of fluids of all kinds.
Dynamic and kinematic viscosity are different quantities
Two viscosities are in common use and they are not alternative units for the same property. Dynamic viscosity (measured in pascal seconds or poise, and handled on this page) describes a fluid's internal resistance to shear. Kinematic viscosity divides that by the fluid's density.
Because the two differ by density, converting between them requires knowing the fluid. There is no fixed factor: two liquids with identical dynamic viscosity but different densities have different kinematic viscosities, which is why the site keeps them on separate converters.
- Poise and stokes are the CGS pair (poise for dynamic, stokes for kinematic), and the "centi" versions dominate because they land on convenient numbers.
- Water near room temperature is about 1 centipoise, which is exactly 0.001 Pa·s. That coincidence is why centipoise became the everyday unit.
- Kinematic viscosity is what falls out of a flow-cup or capillary measurement, since gravity drives the flow and density is therefore already in play.
Oil grades are not viscosity units
Motor oil labelled 10W-40 is not quoting a viscosity in any of the units on this page. Those are SAE grade classifications: bands defined by measurements at specified temperatures, not values that can be converted.
The two numbers describe behaviour at two ends of a range: the figure before the W relates to cold-temperature performance and the one after to viscosity at high operating temperature. A grade maps to a range of viscosities rather than a single value, so it cannot be converted to pascal seconds without the underlying measurement.
- Viscosity falls sharply as temperature rises, so any figure is meaningless without the temperature it was measured at.
- Non-Newtonian fluids change viscosity under shear, so a single number does not describe them at all. Ketchup and paint are everyday examples.
- Always record the measurement temperature alongside a viscosity value; it matters more than the choice of unit.
Frequently Asked Questions
What is dynamic viscosity?
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It is a measure of how much a fluid resists flowing. Honey has high viscosity; water has low viscosity.
What is a centipoise?
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A centipoise is a common viscosity unit; water at 20°C has a viscosity of about 1 centipoise.
How is it different from kinematic viscosity?
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Dynamic viscosity measures resistance to flow directly; kinematic viscosity is dynamic viscosity divided by density.