THE NUMORIX GUIDE
How to use the Viscosity Converter
Last reviewed September 14, 2026
What this calculator does
The converter treats dynamic viscosity in pascal-seconds as its base.
Formula and method
The converter treats dynamic viscosity in pascal-seconds as its base. It uses 1 poise = 0.1 Pa*s, 1 centipoise = 0.001 Pa*s, and 1 lb/(ft*s) = 1.488164 Pa*s, then divides the base value by each factor to produce the other units.
Variables and inputs
Enter a numeric dynamic-viscosity value and choose Pa*s, Poise, Centipoise, or lb/(ft*s). The page continuously shows pascal-seconds and all conversions to six decimals. It does not accept kinematic viscosity or ask for density, temperature, or shear rate.
Worked example
For 1 Pa*s, the result is 10 poise and 1,000 centipoise. Using the engine's factor, 1 / 1.488164 = about 0.671969 lb/(ft*s). Water near room temperature is roughly 1 cP, not 1 Pa*s.
How to interpret the result
Dynamic viscosity measures a fluid's resistance to shear: a larger value means more shear stress is needed for the same velocity gradient. This conversion preserves the dynamic-viscosity quantity; it does not say how a fluid flows through a particular pipe or how its viscosity changes with conditions.
Common mistakes to avoid
Do not substitute centistokes (cSt) for centipoise (cP); cSt is kinematic viscosity and requires density for conversion. Keep Pa*s separate from poise, and do not compare values measured at different temperatures or shear rates as if they were identical material properties.
Assumptions and limitations
The lb/(ft*s) factor is rounded in the engine, and the calculator assumes a scalar dynamic-viscosity value. It does not model temperature dependence, pressure, non-Newtonian behavior, shear history, density, turbulence, or measurement uncertainty. The input handler has no physical-range validation.
Practical use and checks
The Viscosity Converter changes dynamic viscosity among pascal-seconds, poise, centipoise, and pound-foot-seconds. Enter 1 Pa s as a check; the outputs should be 1 Pa s, 10 poise, 1,000 centipoise, and about 0.672 lb/(ft s). Entering 1 centipoise should return 0.001 Pa s, a useful scale check because water near room temperature is often described as roughly 1 cP. The conversion changes units, not the fluid's behavior. Use dynamic viscosity with formulas that expect resistance to shear, and do not confuse it with kinematic viscosity in square meters per second. Temperature, pressure, composition, and shear rate can change viscosity substantially, especially for non-Newtonian fluids, so a catalog value is meaningful only under its stated conditions. The converter uses fixed factors and does not model density, flow speed, turbulence, pressure drop, or a temperature correction. Negative viscosity is not a physical material property even if a raw numeric field can accept it. For a pipe-flow or Reynolds-number calculation, preserve the temperature and whether the source value is dynamic or kinematic before converting. Rounding is usually harmless for a rough unit check but can affect a narrow operating limit or a fluid-selection decision.