Poise-Stokes Converter

This poise-stokes converter will help you easily convert dynamic viscosity to kinematic viscosity and vice versa. In this stokes to poise calculator, you will learn:

• The difference between dynamic and kinematic viscosity;
• The relationship between these two types of viscosities; and
• How to convert poise to stokes, stokes to poise, or either to other viscosity units.

Keep on reading to start learning!

Poise and stokes are units of measure used to quantify viscosity. Poise is a unit of measurement used particularly for dynamic viscosity, while stokes is for kinematic viscosity. Viscosity, which describes a fluid's consistency or "thickness," comes in these two types for some distinct reasons.

The dynamic viscosity tells us how much force is required for a fluid to move at a particular speed. When formulating the mixture of, let's say, a paste in a tube, we want the paste to have a specific dynamic viscosity. That way, it won't be either too hard to squeeze the paste out of the tube or too runny that a lot of paste comes out, even with a little squeezing pressure. Learn more about squeezing pressure on a container with fluids by checking out our manometer calculator.

On the other hand, we use kinematic viscosity to describe the speed of the fluid due to an applied force. One particular use of kinematic viscosity is for fuels. By determining the viscosity of fuels in terms of kinematic viscosity, we get to model the speed fuel droplets that will be sprayed out of an injection nozzle due to applied pressure.

Now that we know the difference between the two types of viscosities let's go back to the measurement units. A poise (P), named after Jean Léonard Marie Poiseuille, who also derived the Poiseuille's law equation, has a value equivalent to 0.1 pascals-second (Pa⋅s). We can also equate 1 poise in terms of other units at values shown in this table:

For kinematic viscosity, we measure it in terms of stokes. Stokes is named after Sir George Gabriel Stokes, who also derived Stokes' law. Learn more about it on our Stokes' law calculator. One stokes (St) is equivalent to 1 square centimeter per second (cm²/s). Here, we also have the other units which have a kinematic viscosity equal to 1 stoke:

We may want to express the viscosity values from one type to another in some cases. Converting from poise to stokes, and even from stokes to poise, is quite an easy thing to do. However, to do that, we need the density of the fluid in question.

Once we know that, we can then use the following formula for conversion:

where:

• ν — Kinematic viscosity in stokes (St);
• η — Dynamic viscosity in poise (P); and
• ρ — Density in grams per cubic centimeter (g/cm³).

We may also see this formula expressed in the form:

In this form, the subscripted T denotes that we can only observe these parameters in a particular fluid at a specific temperature. That indicates that the fluid's density, hence its viscosity, too, changes depending on the fluid's temperature. For simplicity, we'll be using the form without the subscripted T.

Using our conversion formula, we can derive the formula to convert stokes to poise. We only need to multiply both sides of the equation by the density, ρ, to get:

Now that we know how to convert poise to stokes and vice versa, why don't we consider an example? 🙂

Let's say we want to convert the dynamic viscosity of water at 20ºC. At that temperature, water's density, ρ, is approximately 0.9982 g/cm³, and its dynamic viscosity, η, is around 0.010016 poise. Substituting these values in our formula, we have:

ν = 0.010016 poise / 0.9982 g/cm³

ν = 0.010034 stokes (St) or 1.0034 centistokes (cSt)

You can learn more about water viscosity and how temperature affects it by checking out our water viscosity calculator.

Using the poise-stokes calculator makes converting viscosity values a breeze. Here are the steps you can follow when using the poise-stokes converter:

1. Enter the density of the fluid you're interested in.
2. Input your known viscosity.

If you enter a value for the dynamic viscosity, you'll instantly see its equivalent kinematic viscosity and vice versa. You can also convert dynamic and kinematic viscosity values to their other viscosity units using this converter. Simply type in the value of your known viscosity, and then choose another unit from the drop-down menu.