How to use the viscosity converter
- Enter the viscosity in Value.
- In From, choose the unit. Each option shows its kind in brackets, for example “centipoise (cP) (dynamic viscosity)”.
- In To, choose a unit of the same kind.
- Read the answer and the table of every unit of that kind. If you choose one dynamic and one kinematic unit, the tool shows a note explaining ν = μ/ρ instead of a number.
What it does and when to use it
Viscosity is a fluid’s resistance to flow, and it comes in two forms. Dynamic (absolute) viscosity, μ, is measured in Pa·s, poise or centipoise. Rotational viscometers, paint, food and adhesive datasheets usually give this. Kinematic viscosity, ν, is dynamic viscosity divided by density, and is measured in m²/s, stokes or centistokes. Lubricating and hydraulic oils, fuels and flow-cup tests usually give this.
This converter covers eight dynamic and eight kinematic units in one place, and refuses to mix them because that would need the density. Get the density from a datasheet, using the density converter if it is in other units, then divide. There are also separate pages for each kind: the dynamic viscosity converter and the kinematic viscosity converter.
How it works
Each unit is a multiple of its kind’s SI base unit. The result is value × from-factor ÷ to-factor.
| Dynamic unit | Pa·s | Kinematic unit | m²/s |
|---|---|---|---|
| mPa·s, cP | 0.001 | mm²/s, cSt | 0.000001 |
| poise | 0.1 | stokes, cm²/s | 0.0001 |
| micropoise | 0.0000001 | ft²/s | 0.09290304 |
| lb/(ft·s) | 1.48816394357 | ft²/h | 0.0000258064 |
| lbf·s/ft² | 47.8802589803 | in²/s | 0.00064516 |
| reyn | 6,894.75729317 |
The imperial factors are built from the exact pound, foot, inch and standard gravity.
Worked examples
Water-like fluid. 1 cP = 0.001 Pa·s, also shown as 1 mPa·s and 0.01 poise.
Hydraulic oil. ISO VG 46 oil is graded around 46 cSt at 40 °C. 46 cSt = 0.46 stokes (St), or 46 mm²/s.
Mixing kinds. Asking for 1 cP in cSt returns a note that kinematic = dynamic ÷ density (ν = μ/ρ) and that 1 cP of water at about 20 °C is roughly 1.002 cSt.
Limits and tips
- Always note the temperature with a viscosity figure; the unit change does not adjust for it.
- Non-Newtonian fluids such as paint, ketchup or drilling mud have a viscosity that depends on shear rate, so one number tells only part of the story.
- Flow-cup seconds and SUS (Saybolt) are empirical scales, not units, and are not converted here.
Frequently asked questions
How do I convert centipoise to centistokes?
Is 1 cP equal to 1 mPa·s?
Is 1 cSt equal to 1 mm²/s?
What is a reyn?
Why does my oil's viscosity number change with temperature?
Sources
- NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically — NIST, accessed 2026-10-08
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