Centistokes (cSt or ctsk) and Saybolt Universal seconds (SUS, SSU or SUV) are both units of viscosity. Viscosity is a measure of the resistance of a fluid which is being deformed. It can be colloquially described as the “stickiness” of a liquid. Both forms of units are commonly used in various forms of fluid mechanics. The conversion from Centistokes to Saybolt Universal seconds in terms of calculations is not simple. Rather, there are simpler tools that can be used to help the conversion.

Determine whether the centistoke value is greater than or equal to 20.65, or below 20.65.

Square the value.

If the initial centistokes value was greater than or equal to 20.65, add 118.8. If the initial centistokes value was less than 20.65, add 176.28.

Square-root the resulting value.

Add the initial centistokes value to the resulting value.

If the initial centistokes value was greater than or equal to 20.65, multiply 2.272. If the initial centistokes value was less than 20.65, multiply 2.212.

#### Tip

There are websites on-line that calculate estimated converted values of Centistokes and Saybolt Universal seconds that can be easily found through search engines like Google.