Convert Stokes to Square Millimeters per Second
Stokes (St) to Square Millimeter per Second (mm²/s) kinematic viscosity conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 St = 100 mm²/s
1 Stokes = 100 Square Millimeters per Second
1 Square Millimeter per Second = 0.01 Stokes
1 St in every supported unit
Conversion chart: Stokes to Square Millimeters per Second
Conversion table
| Stokes (St) | Square Millimeter per Second (mm²/s) |
|---|---|
| 0.01 St | 1 mm²/s |
| 0.1 St | 10 mm²/s |
| 1 St | 100 mm²/s |
| 2 St | 200 mm²/s |
| 3 St | 300 mm²/s |
| 5 St | 500 mm²/s |
| 10 St | 1000 mm²/s |
| 20 St | 2000 mm²/s |
| 50 St | 5000 mm²/s |
| 100 St | 10000 mm²/s |
| 1000 St | 100000 mm²/s |
Stokes (St)
Definition: The classical CGS unit of kinematic viscosity, named for Irish physicist George Gabriel Stokes, equal to one square centimeter per second.
History: Introduced in the late 19th century as fluid dynamics matured into a quantitative science built on the CGS system, honoring Stokes's foundational work on viscous flow and the Navier-Stokes equations.
Current use: Still the standard reference unit in the oil and lubricant industry worldwide, almost always used through its more practical submultiple, the centistokes.
Square Millimeter per Second (mm²/s)
Definition: A finer metric kinematic viscosity unit, numerically identical to the centistokes, sized for the small values typical of common liquids like water and light oils.
History: A natural SI submultiple of square meter per second, scaled down to match the magnitude of everyday fluids rather than the unwieldy base SI unit.
Current use: Used interchangeably with centistokes in laboratory measurements and viscometer readouts, since the two units are numerically equal.
Supported Units
| Unit | Symbol | In m²/s |
|---|---|---|
| Square Meter per Second | m²/s | 1 m²/s |
| Square Meter per Hour | m²/h | 0.0002777778 m²/s |
| Square Centimeter per Second | cm²/s | 0.0001 m²/s |
| Square Millimeter per Second | mm²/s | 1E-06 m²/s |
| Stokes | St | 0.0001 m²/s |
| Centistokes | cSt | 1E-06 m²/s |
| Millistokes | mSt | 1E-07 m²/s |
| Kilostokes | kSt | 0.1 m²/s |
| Square Foot per Second | ft²/s | 0.09290304 m²/s |
| Square Foot per Hour | ft²/h | 2.58064E-05 m²/s |
| Square Inch per Second | in²/s | 0.00064516 m²/s |
About These Parameters
- Value
- The kinematic viscosity value you want to convert, expressed in the "From" unit. Accepts decimals.
- From Unit
- The unit your input value is currently measured in — a viscometer readout in centistokes, or an SI-based engineering figure in m²/s.
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly.
How Viscosity - Kinematic Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to square meters per second. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Stokes → Square Millimeter per Second: multiply by 100. For example, 1 St × 100 = 100 mm²/s.
Kinematic Viscosity vs. Dynamic Viscosity
This page converts between units of KINEMATIC viscosity (area per time, e.g. m²/s), which is dynamic viscosity divided by density. The site's separate Viscosity - Dynamic Converter covers the underlying force-based quantity (e.g. pascal-seconds) directly. Converting between the two is not a fixed unit conversion the way m²/s to stokes is — it requires the specific fluid's density, since kinematic viscosity = dynamic viscosity ÷ density, and density varies fluid to fluid and with temperature.
Stokes and Centistokes
The stokes (St) and its more practical submultiple, the centistokes (cSt), are CGS-based units that still dominate the oil and lubricant industry despite predating SI. Water at 20°C measures almost exactly 1 cSt, which makes centistokes an intuitive reference point, and motor oil viscosity grades are defined by kinematic viscosity ranges in cSt measured at a standardized 100°C — one reason cSt appears on virtually every oil datasheet and viscometer readout worldwide.
Example
A kinematic viscosity of 1 St equals 100 mm²/s. For scale, water at 20°C measures about 1 cSt (0.000001 m²/s), while a typical SAE 30 motor oil measures roughly 10-12 cSt at 100°C — around ten times more resistant to gravity-driven flow than water.
Frequently Asked Questions
How many Square Millimeters per Second are in 1 Stokes?
1 Stokes (St) equals exactly 100 Square Millimeters per Second (mm²/s).
What is kinematic viscosity?
Kinematic viscosity is a fluid's resistance to flow under gravity alone, equal to its dynamic (absolute) viscosity divided by its density. It's measured in units of area per time, such as square meters per second or, far more commonly in practice, centistokes.
How is kinematic viscosity different from dynamic viscosity?
Dynamic viscosity measures a fluid's resistance to shear force directly (e.g. in pascal-seconds), while kinematic viscosity divides that figure by the fluid's density, capturing how the fluid actually flows under its own weight. Two fluids with the same dynamic viscosity but different densities will have different kinematic viscosities, and vice versa.
How accurate are these conversions?
Every conversion factor used here is the exact, internationally recognized relationship between the underlying area and time units — results are limited only by floating-point display precision, not by rounded conversion constants.
Why is centistokes used for motor oil instead of the SI unit?
The SI unit, square meter per second, is far too large for everyday liquids — water's kinematic viscosity is only 0.000001 m²/s. Centistokes rescales that to a convenient "about 1" for water, which is why the lubricant industry standardized on it long before SI units existed and never switched away.