What this tool does
This tool converts between different units of kinematic viscosity, which measures a fluid's resistance to flow under the influence of gravity. Kinematic viscosity is essential in fluid mechanics, lubrication engineering, and oil analysis. The tool supports conversions between the SI unit (square meters per second), the CGS units (Stokes and centistokes), and imperial units (square feet and square inches per second). Simply enter a value, select your source and target units, and get instant, accurate conversions with a complete reference table showing all supported units.
How it calculates
**Formula:** \`\`\` result = inputValue × (fromUnitFactor / toUnitFactor) \`\`\`
**Where:** - **inputValue** = the kinematic viscosity value in the source unit - **fromUnitFactor** = conversion factor from source unit to m²/s - **toUnitFactor** = conversion factor from target unit to m²/s
**Conversion factors to m²/s (SI base unit):** - **m²/s** = 1 (SI base unit) - **Stokes (St)** = 0.0001 m²/s (equivalent to 1 cm²/s) - **Centistokes (cSt)** = 0.000001 m²/s (1/100 of a Stokes) - **cm²/s** = 0.0001 m²/s (same as Stokes) - **ft²/s** = 0.09290304 m²/s - **in²/s** = 0.00064516 m²/s
**Note:** Kinematic viscosity (ν) = Dynamic viscosity (μ) / Density (ρ)
Who should use this
- **Lubrication engineers** selecting and specifying oils and greases for machinery based on viscosity requirements - **Oil analysts** interpreting used oil analysis reports that typically report kinematic viscosity in centistokes - **HVAC technicians** working with refrigerant oils and compressor lubricants - **Automotive technicians** comparing motor oil viscosity grades and specifications - **Fluid engineers** designing hydraulic systems, pipelines, and pumping equipment - **Chemical engineers** calculating fluid flow characteristics in process equipment - **Quality control technicians** testing lubricant and fuel samples against specifications
Applications
**Oil Analysis:** Used oil analysis programs measure kinematic viscosity (typically in cSt at 40°C and 100°C) to detect contamination, oxidation, or wrong oil usage. A viscosity change of more than 10-15% often indicates a problem requiring investigation.
**Fluid Engineering:** Kinematic viscosity directly affects Reynolds number calculations, which determine whether flow is laminar or turbulent. This is critical for pipe sizing, pump selection, and heat exchanger design.
**HVAC Systems:** Refrigeration compressors require specific oil viscosities for proper lubrication. The oil must flow at low temperatures during startup while maintaining adequate film thickness at operating temperatures.
**Lubricant Selection:** Motor oil viscosity grades (like SAE 5W-30) are based on kinematic viscosity measurements. The first number (5W) relates to cold-start viscosity, while the second (30) indicates viscosity at 100°C.
Worked examples
**Example 1: Converting motor oil viscosity** A motor oil has a kinematic viscosity of 100 cSt at 40°C. Convert to m²/s. - Calculation: 100 cSt × 0.000001 = 0.0001 m²/s - Result: 100 cSt = 0.0001 m²/s = 1 Stokes
**Example 2: Converting from imperial units** A technical specification lists viscosity as 0.001 ft²/s. Convert to centistokes. - First convert to m²/s: 0.001 × 0.09290304 = 0.00009290304 m²/s - Then convert to cSt: 0.00009290304 / 0.000001 = 92.90304 cSt - Result: 0.001 ft²/s = 92.9 cSt
**Example 3: Comparing fluid viscosities** Water has a kinematic viscosity of about 1 cSt at 20°C. SAE 30 motor oil is approximately 100 cSt at 40°C. - Water in Stokes: 1 cSt = 0.01 St - SAE 30 oil in Stokes: 100 cSt = 1.0 St - The oil is 100 times more viscous than water
Unit definitions
**Square meter per second (m²/s):** The SI unit of kinematic viscosity. One m²/s equals 10,000 Stokes, making it a very large unit rarely used for practical measurements.
**Stokes (St):** Named after George Stokes, defined as 1 cm²/s. Commonly used in the CGS system but largely replaced by centistokes for practical applications.
**Centistokes (cSt):** One hundredth of a Stokes (0.01 St). The most common unit in oil analysis and lubricant specifications. Water at 20°C has a viscosity of approximately 1 cSt.
**Square centimeter per second (cm²/s):** Equivalent to Stokes. Used in scientific literature following CGS conventions.
**Square foot per second (ft²/s):** Imperial unit occasionally found in older American engineering references and some industrial specifications.
**Square inch per second (in²/s):** Less common imperial unit, sometimes used in specialized applications.
Limitations
- Kinematic viscosity varies significantly with temperature; this tool does not perform temperature corrections - The tool assumes Newtonian fluid behavior; non-Newtonian fluids (like grease or polymer solutions) may require different measurement approaches - Very high precision applications may require consideration of significant figures beyond what this calculator displays - The tool does not convert between kinematic and dynamic viscosity (which requires knowing the fluid density)
FAQs
**Q: What is the difference between kinematic and dynamic viscosity?** A: Dynamic viscosity (μ) measures internal resistance to flow. Kinematic viscosity (ν) is dynamic viscosity divided by density (ν = μ/ρ). Kinematic viscosity accounts for the fluid's weight, which affects flow under gravity.
**Q: Why do oil specifications use centistokes?** A: Centistokes provide convenient numbers for common fluids. Water is about 1 cSt, light oils are 10-50 cSt, and heavy oils are 100-1000 cSt. Using m²/s would result in very small, awkward numbers.
**Q: At what temperature should viscosity be measured?** A: Standard temperatures are 40°C (104°F) for industrial oils and 100°C (212°F) for engine oils. Always note the temperature when reporting viscosity values.
**Q: How do I convert if I only have dynamic viscosity?** A: Divide dynamic viscosity by density. For example, if dynamic viscosity is 0.001 Pa·s and density is 1000 kg/m³, kinematic viscosity = 0.001/1000 = 0.000001 m²/s = 1 cSt.
Explore Similar Tools
Explore more tools like this one:
- Dynamic Viscosity Converter — Convert dynamic viscosity units including Pa·s, cP,... - Acres to Square Feet Converter — Convert acres to square feet for land and property... - Binary to Decimal Converter — Convert binary numbers to decimal with step-by-step... - Binary to Hexadecimal Converter — Convert binary numbers to hexadecimal with step-by-step... - Binary to Octal Converter — Convert binary numbers to octal with step-by-step...