Kinematic Viscosity Converter
Convert kinematic viscosity between sq m/s, centistokes (cSt), and stokes.
Enter any value to update all units for fluid dynamics and lubrication engineering.
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Kinematic viscosity describes how readily a fluid flows under its own weight. It’s the fluid’s dynamic viscosity divided by its density, which is why the units work out to area per time, m²/s in SI. Where dynamic viscosity answers “how hard is this to stir,” kinematic viscosity answers “how fast will it run downhill.”
Key conversions:
- 1 m²/s = 1,000,000 mm²/s
- 1 stokes (St) = 0.0001 m²/s = 100 mm²/s
- 1 centistokes (cSt) = 0.000001 m²/s = 1 mm²/s
Where common fluids land:
- Water at 20°C: about 1 cSt
- Motor oil (SAE 30): about 100 cSt
- Honey: 2,000–10,000 cSt
The stokes and centistokes come from the cgs system, named after George Stokes, and the centistokes survives mostly because water sits at almost exactly 1 cSt. Industrial oil grading lives here too: the ISO VG number on a lubricant is just its kinematic viscosity in cSt at 40°C.
The division by density is the part that trips people. Two fluids can share the same dynamic viscosity yet have very different kinematic viscosity if their densities differ. Mercury is the classic example. It’s fairly viscous in the dynamic sense, but it’s so dense that its kinematic viscosity comes out lower than water’s. Always check which viscosity a spec is quoting before you compare two fluids.
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