Poise-Stokes Converter
Convert between poise and stokes for dynamic and kinematic viscosity. Free online viscosity converter using ν = η/ρ for physics and fluid mechanics.
About This Calculator
The Poise-Stokes Converter is a free online tool that converts between dynamic viscosity (measured in poise or centipoise) and kinematic viscosity (measured in stokes or centistokes) using the fundamental relationship ν = η / ρ. This calculator is essential for engineers, physicists, chemists, and students working in fluid mechanics, lubrication engineering, food processing, and chemical engineering.
Dynamic viscosity (η) describes a fluid's internal resistance to flow when an external force is applied — think of how much force is needed to stir honey versus water. Kinematic viscosity (ν) describes how quickly a fluid flows under gravity alone — the same honey flows much slower than water when poured. The conversion between these two quantities requires the fluid's density (ρ): kinematic viscosity (St) = dynamic viscosity (P) / density (g/cm³). For the reverse conversion: dynamic viscosity (P) = kinematic viscosity (St) × density (g/cm³).
You can enter any two of the three values (dynamic viscosity, density, kinematic viscosity) and the converter will compute the third automatically. The results panel shows the viscosity values in multiple units including Poise (P), Centipoise (cP), Stokes (St), Centistokes (cSt), and square meters per second (m²/s).
Regional Notes
India (IN): In Indian engineering and academic contexts, viscosity is commonly expressed in poise and stokes (CGS units) or in SI units of Pa·s and m²/s. The IS 12074 standard for lubricants specifies viscosity grades in cSt at 40°C and 100°C.
United States (US): The US uses both CGS units (poise, stokes, centipoise, centistokes) and USC units such as lb/(ft·s) and ft²/s. SAE viscosity grades for motor oils are specified in cSt at 100°C and cP at 150°C.
United Kingdom (UK): The UK uses SI units (Pa·s, m²/s) alongside CGS units. British Standard BS 2000-71 specifies kinematic viscosity measurement methods. Industrial lubricants often reference viscosity in cSt at 40°C.
Frequently Asked Questions
What is the difference between poise and stokes?
Poise (P) is the CGS unit of dynamic viscosity, which measures a fluid's internal resistance to flow under an applied force. Stokes (St) is the CGS unit of kinematic viscosity, which measures the fluid's resistance to flow under the influence of gravity. The two are related by the fluid's density: kinematic viscosity = dynamic viscosity / density.
How do you convert poise to stokes?
To convert poise to stokes, divide the dynamic viscosity in poise by the density of the fluid in grams per cubic centimeter (g/cm³). The formula is ν = η / ρ, where ν is kinematic viscosity in stokes, η is dynamic viscosity in poise, and ρ is density in g/cm³.
What is the relationship between poise and centipoise?
One poise (P) equals 100 centipoise (cP). Centipoise is more commonly used in practice because most fluids have dynamic viscosities in the centipoise range. For example, water at 20°C has a dynamic viscosity of approximately 1.002 cP.
How many stokes in a poise for water?
For water at 20°C (density 0.9982 g/cm³, dynamic viscosity 1.0016 cP = 0.010016 P), the kinematic viscosity is approximately 0.010034 St or 1.0034 cSt. The exact conversion depends on the fluid's density.
What units does the Poise-Stokes converter support?
Our Poise-Stokes converter supports Poise (P) and Centipoise (cP) for dynamic viscosity, Stokes (St) and Centistokes (cSt) for kinematic viscosity, and g/cm³ for density. Results are also provided in m²/s for kinematic viscosity.
Is this Poise-Stokes converter free to use?
Yes, this Poise-Stokes converter is completely free to use with no registration required. You can share your calculations via the URL which saves all input values.