Viscosity converter
Convert dynamic viscosity units such as Pa·s and cP, and kinematic viscosity units such as m²/s and cSt. Enter the density in kg/m³ under the same measurement conditions only when converting between dynamic and kinematic viscosity. Check the conditions used and the converted value, then copy the number and unit. Temperature differences are not corrected.
What you can do
Use consistent viscosity units across documents
Supports Pa·s, mPa·s, cP, P, m²/s, St, cSt and mm²/s. Select the source and target units to convert.
Convert between viscosity types using density
Enter density when converting between dynamic and kinematic viscosity. Density is not needed for conversions between units of the same type.
Check results with their conditions
Check the input value and density used as well as the converted value and output unit. You can copy the result's number and unit.
How to use
Enter a value & source unit
Enter the value to convert and select the unit shown in your document.
Specify the target unit & density if needed
Select the target unit. When converting between dynamic and kinematic viscosity, enter the density in kg/m³ measured under the same conditions.
Convert & check the conditions
Select “Convert” and check the result's unit and conditions used. Copy the result if needed.
Useful for
Use consistent units across specifications
Convert values written in different units, such as cP and Pa·s, to the same unit for comparison across documents.
Check the relationship between dynamic & kinematic viscosity
For a fluid with a known density, you can convert dynamic viscosity to kinematic viscosity or vice versa.
The relationship between dynamic viscosity, kinematic viscosity & density
Dynamic & kinematic viscosity are different quantities
The SI unit of dynamic viscosity is Pa·s, and that of kinematic viscosity is m²/s. Even if the unit names sound similar, they are different physical quantities.
Density connects the two
Kinematic viscosity is dynamic viscosity divided by density. Conversely, multiplying kinematic viscosity by density gives dynamic viscosity. Density units are also made consistent for the calculation.
Use matching measurement conditions, including temperature
Both viscosity and density vary with measurement conditions. This tool converts units and does not correct values for different temperatures.
Frequently asked questions
Do cP and cSt have the same numerical value?
Not always. cP is a unit of dynamic viscosity, while cSt is a unit of kinematic viscosity. Converting between them requires density; their numerical values match at 1000kg/m³.
What if there is no density input field?
You can convert units of the same type without using density. Examples include cP to Pa·s and cSt to m²/s.
What density should I enter?
Enter a value for the fluid obtained under the same conditions as the viscosity measurement, such as the same temperature. The default of 1000kg/m³ does not apply to every fluid.
Can I compare measurements taken at different temperatures?
You can convert values to the same unit, but temperature differences are not corrected. Check the measurement conditions when comparing values.
Inputs & results
- Input
- A value of 0 or greater, source and target units, and density for conversions between viscosity types.
- Result
- The converted value in your selected unit. Changing the input or units clears the previous result.
- Copy
- You can copy the result's number and unit. Temperature correction and grade classification are not included.