How to Use the Viscosity Unit Converter
Oil, lubricant, and chemical fluid spec sheets often list viscosity in cP (centipoise) or cSt (centistokes), which makes comparing products across brands confusing. Enter the fluid's density along with your value, and this calculator converts between the two units for you.
cP is absolute (dynamic) viscosity — the raw resistance a fluid has to flowing — while cSt is kinematic viscosity, which divides that resistance by density. For fluids close to water's density (around 1.0 g/mL), cP and cSt come out nearly identical, but for oils with a lower density, the two values diverge noticeably. If you don't know the exact density, check the product's spec sheet or MSDS for the most accurate result.
Frequently Asked Questions
cP (centipoise) measures absolute (dynamic) viscosity, while cSt (centistokes) measures kinematic viscosity, which accounts for density. Convert between them with 'cSt = cP / density (g/mL)'.
Water is about 1.0 g/mL, and typical engine oil is about 0.85-0.9 g/mL. For an exact value, check the product's spec sheet or MSDS.