Kinematic Viscosity Converter

Kinematic viscosity (ν) is how easily a fluid flows under its own weight: its dynamic viscosity divided by its density, ν = μ / ρ. Its SI unit is the square meter per second (m²/s), but fluids are usually given in centistokes (cSt), which equal square millimeters per second: 1 cSt = 1 mm²/s.

For a sense of scale: water at 20 °C is about 1 cSt, a light motor oil 30–100 cSt at 40 °C, and honey thousands. Industrial and hydraulic oil grades such as ISO VG 46 are named after their viscosity in cSt at 40 °C.

How to convert kinematic viscosity

Type a value into any field, and every other unit is calculated at once. Centistokes are entered in the mm²/s field. For example, an oil of 46 cSt:

1. In stokes: divide by 100.

   46 / 100 = 0.46 St

2. In ft²/s: multiply by 0.0000107639.

   46 * 0.0000107639 = 0.0004951 ft²/s

To get a dynamic viscosity, multiply by the density: 46 cSt at 870 kg/m³ is about 0.000046 * 870 = 0.04 Pa·s. Dynamic viscosities are converted in the Dynamic Viscosity Converter.

Common conversions

Units of kinematic viscosity

Metric Units

• Meter² / second (m²/s): The kinematic viscosity in square meters per second. The standard unit for kinematic viscosity.
  Conversion Factor: 1 m²/s = 3,600 m²/h

• Meter² / hour (m²/h): Kinematic viscosity measured in square meters per hour. A unit that is 3,600 times smaller than the standard unit.
  Conversion Factor: 1 m²/h = 1 m² / 3,600 s = 0.00027778 m²/s

• Centimeter² / second (cm²/s): The kinematic viscosity in square centimeters per second. A unit that is 10,000 times smaller than the standard unit.
  Conversion Factor: 1 cm²/s = 0.0001 m²/s

• Millimeter² / second (mm²/s): Kinematic viscosity measured in square millimeters per second. A unit that is 1,000,000 times smaller than the standard unit.
  Conversion Factor: 1 mm²/s = 0.000001 m²/s

Imperial Units

• Foot² / second (ft²/s): The kinematic viscosity in square feet per second. The most commonly used unit of the imperial units for kinematic viscosity.
  Conversion Factor: 1 ft²/s = 3,600 ft²/h = 0.0929 m²/s

• Foot² / hour (ft²/h): The kinematic viscosity in square feet per hour. A unit that is 3,600 times smaller than ft²/s.
  Conversion Factor: 1 ft²/h = 1 ft² / 3,600 s = 0.00027778 ft²/s

• Inch² / second (in²/s): Kinematic viscosity measured in square inches per second. A unit that is 144 times smaller than ft²/s.
  Conversion Factor: 1 in²/s = 0.00694444 ft²/s

CGS Units

• Stokes (St): The basic unit of kinematic viscosity in the centimeter-gram-second (CGS) system. It is equal to one square centimeter per second.
  Conversion Factor: 1 St = 1 cm²/s = 0.0001 m²/s

• Kilostokes (kSt): A unit of kinematic viscosity equal to 1,000 stokes.
  Conversion Factor: 1 kSt = 1,000 St

• Megastokes (MSt): A high unit of kinematic viscosity, equivalent to 1,000,000 stokes.
  Conversion Factor: 1 MSt = 1,000,000 St

• Millistokes (mSt): A subunit of kinematic viscosity, equal to one-thousandth of a stoke.
  Conversion Factor: 1 mSt = 0.001 St

• Microstokes (µSt): A very small unit of kinematic viscosity, equal to one-millionth of a stoke.
  Conversion Factor: 1 µSt = 0.000001 St