Kinematic Viscosity Converter
Convert between kinematic viscosity units including stokes, centistokes, m2/s, and more.
1 cSt =
1
Square millimeter per second (mm2/s)
1 cSt in all units
Quick Reference
1 Stokes
= 100 cSt
1 cSt
= 1 mm2/s
Water at 20C
~1 cSt
Motor oil
~100-300 cSt
What is Kinematic Viscosity?
Kinematic viscosity is a measure of a fluid's internal resistance to flow under the influence of gravity, expressed as the ratio of dynamic viscosity to density. Unlike dynamic viscosity, which measures resistance to shear forces, kinematic viscosity describes how readily a fluid deforms and flows under its own weight. It is measured in square meters per second (m²/s) in the SI system, though the CGS unit Stokes (St) and centistokes (cSt) remain widely used in engineering and industry.
The concept is crucial because it accounts for the fluid's density. A thick, heavy fluid might have high dynamic viscosity but flow more readily than a light, thin fluid under gravity because of its greater weight. Kinematic viscosity captures this interplay between viscosity and density in a single number. For example, glycerin has a very high dynamic viscosity but also a high density, so its kinematic viscosity is moderate compared to lighter oils.
Industries that work with fluids — petroleum refining, automotive lubrication, food processing, pharmaceutical manufacturing, and chemical engineering — all rely on kinematic viscosity measurements. Oil grades like 5W-30 and 10W-40 are defined by their kinematic viscosity at specific temperatures. This converter translates between centistokes, stokes, square meters per second, square centimeters per second, and other kinematic viscosity units.
Kinematic Viscosity Conversion Formula
Kinematic viscosity units are related by simple multiplicative factors based on the metric system's decimal structure.
Kinematic Viscosity Conversion
Where:
- ν_target= Kinematic viscosity in the target unit
- ν_source= Kinematic viscosity in the source unit
- factor_source= Conversion factor of the source unit relative to m²/s
- factor_target= Conversion factor of the target unit relative to m²/s
Viscosity Unit Reference
The following table shows common kinematic viscosity units and their relationships to the base SI unit, along with typical applications.
| Unit | Symbol | Relation to m²/s | Common Use |
|---|---|---|---|
| Square meter/second | m²/s | 1 | SI base unit |
| Stokes | St | 0.0001 | Laboratory measurements |
| Centistokes | cSt | 0.000001 | Oil grades, industrial |
| Square mm/second | mm²/s | 0.000001 | Equals 1 cSt exactly |
| Square foot/second | ft²/s | 0.09290304 | US engineering |
How to Use This Calculator
The kinematic viscosity converter provides accurate translations between all common units:
- Enter the viscosity value: Type the numerical value you want to convert.
- Select the source unit: Choose from m²/s, cm²/s, mm²/s, Stokes, centistokes, ft²/s, ft²/hr, or in²/s.
- Select the target unit: Pick the unit you want to convert to.
- View the result: The calculator instantly displays the converted value.
- See all conversions: The results table shows your input value expressed in every supported unit simultaneously.
- Swap units: Use the swap button to quickly reverse the conversion direction.
Real-World Applications
Kinematic viscosity conversion is essential in petroleum and lubricant engineering. Motor oil grades like 5W-30 and 10W-40 are defined by their kinematic viscosity at 100°C. Engine designers and mechanics must specify oils with the correct viscosity to ensure proper lubrication, fuel efficiency, and engine longevity. Converting between centistokes and other units helps cross-reference international specifications and standards.
In food and beverage processing, the viscosity of liquids affects product quality, processing equipment selection, and quality control. Honey, chocolate syrup, ketchup, and other viscous products are manufactured to specific viscosity standards. Converting between the centipoise (dynamic) and centistokes (kinematic) measurements used in different parts of the industry ensures consistency across production facilities worldwide.
Chemical and pharmaceutical manufacturing requires precise viscosity control for product quality and safety. Drug formulations, paint coatings, adhesives, and polymer solutions are all manufactured to specific viscosity specifications. Quality control labs often receive instruments calibrated in different units, making accurate conversion essential for maintaining consistency and regulatory compliance.
Worked Examples
Converting Centistokes to Stokes
Problem:
Convert 500 cSt to Stokes.
Solution Steps:
- 11 St = 100 cSt
- 2Divide: 500 ÷ 100
- 3500 cSt = 5 St
Result:
500 cSt = 5 St
Converting mm²/s to m²/s
Problem:
Convert 25 mm²/s to square meters per second.
Solution Steps:
- 11 mm²/s = 0.000001 m²/s
- 2Multiply: 25 × 0.000001
- 325 mm²/s = 0.000025 m²/s
- 4Also: 25 mm²/s = 25 cSt (since 1 cSt = 1 mm²/s exactly)
Result:
25 mm²/s = 0.000025 m²/s = 25 cSt
Converting Motor Oil Viscosity
Problem:
What is the kinematic viscosity of SAE 30 motor oil in m²/s if it measures 100 cSt at 100°C?
Solution Steps:
- 11 cSt = 0.000001 m²/s
- 2Multiply: 100 × 0.000001
- 3100 cSt = 0.0001 m²/s = 1 Stokes
Result:
SAE 30 at 100°C: 100 cSt = 0.0001 m²/s = 1 St
Tips & Best Practices
- ✓1 cSt = 1 mm²/s exactly — these are the same unit with different names
- ✓1 Stokes = 100 cSt — the conversion is straightforward
- ✓Water at 20°C ≈ 1 cSt — a useful reference point
- ✓Motor oil at 100°C typically ranges from 10-30 cSt
- ✓Viscosity always decreases with increasing temperature for liquids
- ✓Oil grades (5W-30, 10W-40) are defined by viscosity at specific temperatures
Frequently Asked Questions
Sources & References
Last updated: 2026-06-06
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
Formula Source: NIST Guide to SI Units
by National Institute of Standards