Viscosity - Kinematic Converter
Convert kinematic viscosity between square meters, square centimeters, square millimeters, square feet or square inches per second, and stokes with every SI prefix. Pick a source and a target unit, enter a value and read the result instantly.
Select two units to see the conversion factor.
This tool converts kinematic viscosity (area per time). It cannot turn it into dynamic viscosity (Pa·s, poise) because that needs the fluid density: use the Dynamic Viscosity Converter for those units.
Kinematic Viscosity Formula
Every kinematic viscosity unit is an area divided by a time, so each one is a fixed multiple of one reference unit, the square meter per second (m²/s). To convert, multiply the value by the size of the source unit in m²/s, then divide by the size of the target unit in m²/s. The relationships are exact: 1 stokes = 10⁻⁴ m²/s, 1 mm²/s = 1 centistokes = 10⁻⁶ m²/s, 1 ft = 0.3048 m, 1 in = 0.0254 m and 1 h = 3,600 s.
What Is Kinematic Viscosity?
Kinematic viscosity describes how quickly a fluid flows under gravity, or more precisely how fast momentum diffuses through it. It is the dynamic viscosity divided by the density of the fluid, ν = μ ÷ ρ, which gives it the dimensions of an area per time. The SI unit is the square meter per second (m²/s), but in practice liquids are rated in square millimeters per second (mm²/s).
The CGS unit is the stokes (St), equal to 1 cm²/s or 10⁻⁴ m²/s, named after George Stokes. Because that is large for most liquids, the centistokes (cSt), one hundredth of a stokes, is the everyday unit. One centistokes equals exactly one mm²/s, so the two can be read as the same number. Water at about 20 °C has a kinematic viscosity of roughly 1 cSt, and lubricating oils are graded by their kinematic viscosity at 40 °C, for example ISO VG 32 means about 32 mm²/s.
Kinematic viscosity differs from dynamic viscosity (Pa·s, poise), which measures the shear resistance itself. To go from one to the other you need the density: ν = μ ÷ ρ. For example a liquid with μ = 0.85 Pa·s and ρ = 900 kg/m³ has ν = 0.85 ÷ 900 = 9.444 × 10⁻⁴ m²/s, or about 944.4 cSt. Because density varies with temperature and substance, the converter only changes between kinematic units.
Supported Units
This converter supports the following 24 kinematic viscosity units, including the stokes with every SI prefix from exa to atto. The last column shows how many square meters per second one unit equals. A square meter per second is a very large unit for liquids, which is why mm²/s and cSt are used so often.
| Unit | Symbol | Value in m²/s |
|---|---|---|
| Square meter per second | m²/s | 1 |
| Square meter per hour | m²/h | 0.0002777777778 |
| Square centimeter per second | cm²/s | 0.0001 |
| Square millimeter per second | mm²/s | 1e-6 |
| Square foot per second | ft²/s | 0.09290304 |
| Square foot per hour | ft²/h | 2.58064e-5 |
| Square inch per second | in²/s | 0.00064516 |
| Stokes | St | 0.0001 |
| Exastokes | ESt | 1e+14 |
| Petastokes | PSt | 100,000,000,000 |
| Terastokes | TSt | 100,000,000 |
| Gigastokes | GSt | 100,000 |
| Megastokes | MSt | 100 |
| Kilostokes | kSt | 0.1 |
| Hectostokes | hSt | 0.01 |
| Dekastokes | daSt | 0.001 |
| Decistokes | dSt | 1e-5 |
| Centistokes | cSt | 1e-6 |
| Millistokes | mSt | 1e-7 |
| Microstokes | µSt | 1e-10 |
| Nanostokes | nSt | 1e-13 |
| Picostokes | pSt | 1e-16 |
| Femtostokes | fSt | 1e-19 |
| Attostokes | aSt | 1e-22 |
How to Use the Viscosity - Kinematic Converter
- Type the kinematic viscosity in the value box. Decimals and scientific notation such as 0.0025 or 2.5e-3 are accepted.
- Choose the From unit and the To unit.
- The result appears instantly, or press Convert Now. Very large or very small results are shown in scientific notation.
- Use Swap Units to reverse the conversion, Copy Result to copy the answer, open Show this value in all units for a full list, and Clear to start again.
Step-by-step by hand
- Find the size of each unit in the common base unit (m²/s): 1 cSt = 1e-6 m²/s and 1 m²/s = 1 m²/s.
- Divide the source size by the target size to get the conversion factor: 1e-6 ÷ 1 = 1e-6, so 1 cSt = 1e-6 m²/s.
- Multiply by your value: 32 cSt × 1e-6 = 3.2e-5 m²/s.
Viscosity cannot be negative, so only zero and positive numbers are accepted.
Common Kinematic Viscosity Conversions
- Hydraulic oil ISO VG 32: 32 cSt equals 3.2e-5 m²/s and 0.32 St.
- Water at room temperature: about 1 mm²/s equals 1 cSt and 1e-6 m²/s.
- CGS to SI: 1 stokes equals 100 centistokes and 1 cm²/s.
- Heavy oil: 460 cSt equals 460 mm²/s or 1.656 m²/h.
- Imperial data: 0.001 ft²/s equals 92.90304 cSt.
- Per hour: 1 m²/h equals 277.7777778 mm²/s.
- Per square inch: 1 in²/s equals 645.16 mm²/s.
Centistokes Conversion – Common Values
Quick reference for frequently used values
| Centistokes (cSt) | mm²/s | m²/s | Stokes (St) | ft²/s |
|---|---|---|---|---|
| 1 | 1 | 1e-6 | 0.01 | 1.076391042e-5 |
| 5 | 5 | 5e-6 | 0.05 | 5.381955208e-5 |
| 10 | 10 | 1e-5 | 0.1 | 0.0001076391042 |
| 15 | 15 | 1.5e-5 | 0.15 | 0.0001614586563 |
| 22 | 22 | 2.2e-5 | 0.22 | 0.0002368060292 |
| 32 | 32 | 3.2e-5 | 0.32 | 0.0003444451333 |
| 46 | 46 | 4.6e-5 | 0.46 | 0.0004951398792 |
| 68 | 68 | 6.8e-5 | 0.68 | 0.0007319459083 |
| 100 | 100 | 0.0001 | 1 | 0.001076391042 |
| 150 | 150 | 0.00015 | 1.5 | 0.001614586563 |
| 220 | 220 | 0.00022 | 2.2 | 0.002368060292 |
| 460 | 460 | 0.00046 | 4.6 | 0.004951398792 |
| 1,000 | 1,000 | 0.001 | 10 | 0.01076391042 |
Where and Why This Conversion Is Used
- Lubrication and hydraulics: oil grades such as ISO VG are defined by kinematic viscosity at 40 °C, usually in cSt or mm²/s.
- Fuels and petroleum products: specifications for diesel, fuel oil and bitumen state kinematic viscosity limits.
- Fluid dynamics: the Reynolds number uses ν directly, so values from data sheets are converted to m²/s.
- Pipeline and pump sizing: pressure-drop charts are tabulated against kinematic viscosity.
- Chemistry and food technology: capillary viscometers measure ν, and results are reported in cSt or mm²/s.
- US and older references: ft²/s, ft²/h and in²/s appear in imperial engineering handbooks.
For shear resistance in Pa·s or poise use the Viscosity - Dynamic Converter. Flow rates are covered by the Flow Converter.