Viscosity Converter

A viscosity converter for dynamic viscosity (also called absolute viscosity) switches between Pa·s, mPa·s, centipoise (cP), poise, and lb/(ft·s). This free tool helps with fluid mechanics homework, lubricant datasheets, and lab notes — all conversion runs locally in your browser.

The meaning of viscosity is a fluid's resistance to flow — how thick or sticky it feels when layers slide past each other. Defined viscosity in SI is measured as dynamic viscosity in pascal-seconds (Pa·s). A viscous fluid or viscous liquid has high viscosity; a low viscous fluid flows easily (water, alcohol).

Industry and textbooks often quote centipoise (cP). SI uses pascal-seconds (Pa·s). The exact link:

1 cP = 1 mPa·s = 0.001 Pa·s  ·  1 poise (P) = 100 cP = 0.1 Pa·s

Searches like centipoise to pa s, centipoise viscosity, and cp to pa s use multiply-by-0.001. Example: 100 cP = 0.1 Pa·s · 1,000 cP = 1 Pa·s.

Dynamic viscosity for water at ~20°C is about 1 mPa·s (1 cP) — a common anchor in viscosity class 11 physics and fluid mechanics viscosity problems.

Two related quantities appear in physics viscosity and viscosity chemistry:

• Dynamic viscosity (μ) — force per area per velocity gradient; units Pa·s, cP, poise. This tool converts these.
• Kinematic viscosity (ν) — dynamic viscosity divided by density; units m²/s, stokes (St), centistokes (cSt). 1 cSt = 1 mm²/s.

ν = μ / ρ  ·  μ = ν × ρ

Searches like dynamic to kinematic viscosity, kinematic viscosity to dynamic viscosity, absolute viscosity to kinematic viscosity, and centipoise to mm2 s need density ρ from the Density Converter. For water at 20°C (ρ ≈ 1,000 kg/m³): 1 cP → ν ≈ 1 mm²/s (1 cSt) — the numeric coincidence students learn in viscosity class 11.

Density and viscosity are separate properties; density to viscosity is not a direct unit conversion — use ν = μ/ρ when both are known.

High viscosity meaning / high viscous liquid: resists flow strongly. Low viscosity meaning / low viscous liquid: pours quickly.

Approximate dynamic viscosity at room temperature (cP):

• Air ~0.018 cP (air dynamic viscosity — gases are low μ)
• Water ~1 cP
• Methanol / ethanol ~0.5–0.6 cP (alcohol viscosity, ethyl alcohol viscosity)
• Gasoline ~0.4–0.8 cP
• Motor oil 100–500+ cP (lubricant viscosity)
• Glycerol ~950–1,400 cP (glycerol viscosity — very viscous)
• Honey 2,000–10,000+ cP (honey viscosity — temperature dependent)

Oil and water viscosity: oil is typically much higher μ than water. Most viscous liquid contenders include molten polymers and pitch — values far above everyday cP ranges.

A newtonian fluid has constant μ regardless of shear rate — water, air, and light oils are examples (example of newtonian fluid). Non newton fluid / newton and non newtonian fluid behaviour: apparent viscosity changes with stirring speed.

Pseudoplastic fluids (shear-thinning — ketchup, paint) and thixotropic fluid examples (gel over time) need a stated shear rate when quoting μ. This converter scales the numeric value between unit labels — it does not model shear dependence. Apparent viscosity and intrinsic viscosity (polymers in solution) are specialised measures beyond simple cP ↔ Pa·s.

Blood viscosity is shear-dependent and clinically reported under standard conditions — convert quoted cP or mPa·s values here once a single number is given.

Measuring viscosity and use of viscometer / viscometer use belong in the lab, not in unit conversion — but results arrive in cP, St, or seconds on industry scales:

• Capillary viscometer / Ostwald viscometer — kinematic ν from flow time
• Rotating viscometer — dynamic μ from torque
• Falling ball viscometer / falling sphere viscometer — Stokes' law for μ
• Redwood viscometer / Saybolt universal viscometer — efflux seconds (industry); convert to cSt via published tables

After a measurement is expressed in cP or Pa·s, this viscosity unit tool normalises to SI or CGS labels.

Temperature and viscosity / temperature viscosity: most liquids become less viscous when heated (honey pours faster when warm). This converter does not adjust for temperature — enter the value at the temperature stated on your datasheet.

Dimensional analysis of viscosity / viscosity dimensional analysis: dynamic viscosity [μ] = M/(L·T) — Pa·s = kg/(m·s). Kinematic ν = m²/s. That distinction underpins dynamic and kinematic viscosity in viscosity explained textbooks.

This page converts dynamic viscosity units only: Pa·s, mPa·s, cP, poise, lb/(ft·s). It does not convert eddy viscosity (turbulence modelling), relative/intrinsic viscosity (polymers), or Saybolt/Redwood seconds directly — look up equivalent cSt or cP from standard tables first, then convert here.