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Viscosity Conversion
Tool Description
Viscosity Conversion is an online viscosity unit converter supporting dynamic viscosity units (Pa·s, mPa·s, P, cP, kg/(m·s), lb/(ft·s), lbf·s/ft²) and kinematic viscosity units (m²/s, cSt, St). Enter any value and unit to instantly see corresponding results for all units of the same type, ideal for chemical engineering, lubricant selection, food processing, materials science, and fluid mechanics research.
How to Use
- Enter a Value
Input the value to convert in the input field, supporting integers and decimals such as
100,0.89 - Select Source Unit
Choose the viscosity unit from the dropdown list. Dynamic and kinematic viscosity are grouped separately. Note: dynamic and kinematic viscosity are different physical quantities and only convert within their own type
- View Results
Click "Convert" or press Enter to display corresponding values in all units of the same type. Each result has a copy button for convenience
Use Cases
- Chemical & Petroleum Industry: Viscosity is a key quality indicator for lubricants, fuel oils, and other petroleum products. Different countries and standards use different viscosity units (e.g., cSt in Western countries, mPa·s in China). Quickly convert and compare product specifications
- Food Processing: The viscosity of foods like jam, syrup, and chocolate directly affects texture and processing. R&D and quality control require conversions between centipoise (cP) and pascal-second (Pa·s)
- Fluid Mechanics & Materials Science: In fluid mechanics calculations, polymer research, and coating formulation design, conversions between different viscosity unit systems are frequently needed. This tool quickly handles dynamic and kinematic viscosity conversions
Core Advantages
- Daily Free Quota
Free usage is provided to every user every day, covering everyday lightweight conversions at zero cost. Open and use instantly without installation.
- Privacy & Security
All conversions are performed locally in your browser. Your data never leaves your device, giving you 100% privacy protection.
- Wide Unit Coverage
Covers both dynamic and kinematic viscosity systems with 10 commonly used units in total. One input instantly returns all results in the same category.
- Accurate Results
Uses international standard conversion factors and high-precision floating-point arithmetic, with smart decimal rounding for trustworthy results.
- One-Click Copy
Every result comes with a copy button on the right. Click to copy the value for easy pasting into documents, spreadsheets, or chat tools.
Dynamic Viscosity Conversion Table
The following table shows the conversion relationships between dynamic viscosity units, with pascal-second (Pa·s) as the base unit:
| Unit Name | Abbreviation | Conversion Relationship | Equivalent Pa·s |
|---|---|---|---|
| Pascal-second | Pa·s | 1 Pa·s = 1 kg/(m·s) | 1 |
| Millipascal-second | mPa·s | 1 mPa·s = 0.001 Pa·s | 0.001 |
| Poise | P | 1 P = 0.1 Pa·s | 0.1 |
| Centipoise | cP | 1 cP = 1 mPa·s = 0.001 Pa·s | 0.001 |
| Kilogram per meter-second | kg/(m·s) | 1 kg/(m·s) = 1 Pa·s | 1 |
| Pound per foot-second | lb/(ft·s) | 1 lb/(ft·s) ≈ 1.48816 Pa·s | 1.4881639436 |
| Pound-force second per square foot | lbf·s/ft² | 1 lbf·s/ft² ≈ 47.8803 Pa·s | 47.8802589803 |
Kinematic Viscosity Conversion Table
The following table shows the conversion relationships between kinematic viscosity units, with square meter per second (m²/s) as the base unit:
| Unit Name | Abbreviation | Conversion Relationship | Equivalent m²/s |
|---|---|---|---|
| Square meter per second | m²/s | 1 m²/s = 1 m²/s | 1 |
| Stokes | St | 1 St = 0.0001 m²/s | 0.0001 |
| Centistokes | cSt | 1 cSt = 1 mm²/s = 0.000001 m²/s | 0.000001 |
Reference Viscosity Values for Common Substances
The following table shows viscosity values for common substances at room temperature and atmospheric pressure, for reference:
| Substance | Dynamic Viscosity | Kinematic Viscosity |
|---|---|---|
| Air (20°C) | ~ 0.018 mPa·s | ~ 15 cSt |
| Water (20°C) | ~ 1.002 mPa·s | ~ 1.004 cSt |
| Milk | ~ 1.5 mPa·s | ~ 1.3 cSt |
| SAE 10W Motor Oil | ~ 10 mPa·s | ~ 8 cSt |
| SAE 30 Motor Oil | ~ 100 mPa·s | ~ 80 cSt |
| SAE 40 Motor Oil | ~ 500 ~ 1,000 mPa·s | ~ 400 ~ 800 cSt |
| Honey | ~ 1,000 ~ 5,000 mPa·s | - |
| Glycerin (Glycerol) | ~ 10,000 ~ 50,000 mPa·s | - |
| Asphalt/Glass (Room Temp) | ~ 10⁹ ~ 10¹² Pa·s | - |
Relationship Between Dynamic and Kinematic Viscosity
Dynamic viscosity (symbol μ or η) and kinematic viscosity (symbol ν) are two different physical quantities describing fluid viscosity. Dynamic viscosity measures the internal friction resistance to shear deformation in a fluid, with the SI unit of pascal-second (Pa·s). Kinematic viscosity is the ratio of dynamic viscosity to fluid density, with the SI unit of square meter per second (m²/s).
The relationship between the two is: ν = μ / ρ, i.e., kinematic viscosity = dynamic viscosity ÷ density. Therefore, given the fluid density, kinematic viscosity can be calculated from dynamic viscosity and vice versa. For example, at 20°C, water has a dynamic viscosity of approximately 1.002 mPa·s and a density of approximately 998 kg/m³, giving a kinematic viscosity of ν = 1.002×10⁻³ / 998 ≈ 1.004×10⁻⁶ m²/s = 1.004 cSt. This tool displays the two types separately because they cannot be directly interconverted without knowing density. Please select the appropriate unit group as needed.
FAQ
Pascal-second (symbol Pa·s) is the standard SI unit of dynamic viscosity, defined as: when two parallel layers of fluid 1 meter apart move at a relative velocity of 1 m/s, if the shear stress per unit area is 1 pascal (i.e., 1 N/m²), the dynamic viscosity of the fluid is 1 Pa·s. 1 Pa·s is equivalent to 1 kg/(m·s) = 1 N·s/m². Pascal-second is a relatively large viscosity unit; everyday liquids are typically in the mPa·s range.
Poise (symbol P) is the dynamic viscosity unit in the CGS (centimeter-gram-second) system, named after French physicist Jean Léonard Marie Poiseuille. 1 P = 0.1 Pa·s, 1 cP = 0.01 P = 1 mPa·s = 0.001 Pa·s. Centipoise (cP) is one of the most commonly used viscosity units in industry because 1 cP is exactly equal to 1 mPa·s, with identical numerical values. For example, at 20°C, water has a dynamic viscosity of approximately 1.002 cP = 1.002 mPa·s.
Stokes (symbol St) is the kinematic viscosity unit in the CGS system, named after British physicist George Gabriel Stokes. 1 St = 1 cm²/s = 0.0001 m²/s = 100 cSt. Centistokes (cSt) is one hundredth of a stokes, 1 cSt = 1 mm²/s = 10⁻⁶ m²/s. Centistokes is the most commonly used kinematic viscosity unit in lubricant specifications; for example, SAE 30 motor oil has a kinematic viscosity of approximately 9.3~12.5 cSt at 100°C. The ISO VG classification system also uses cSt values at 40°C.
No, they cannot be directly converted without knowing the fluid density. Dynamic viscosity (μ) describes the "internal friction" of a fluid, measured in Pa·s; kinematic viscosity (ν) describes the "ratio of internal friction to inertial force" in a fluid, measured in m²/s. The relationship is ν = μ / ρ (ρ is density). For example, two fluids with the same dynamic viscosity will have different kinematic viscosities if their densities differ. In the lubricant industry, kinematic viscosity (cSt) is typically used to label oil viscosity grades; in chemical engineering and rheology, dynamic viscosity (mPa·s or cP) is commonly used. This tool displays the two types separately—selecting a dynamic viscosity unit shows only dynamic viscosity results, and selecting a kinematic viscosity unit shows only kinematic viscosity results.
No. All conversion calculations are performed entirely in your browser locally using pure JavaScript math. Your input data never leaves your device, so please feel free to use it.
This tool uses JavaScript double-precision floating-point numbers (64-bit IEEE 754) for calculations, which is sufficiently accurate for most everyday scenarios. Poise and centipoise have a strict decimal relationship with Pa·s (1 P = 0.1 Pa·s, 1 cP = 0.001 Pa·s), as do stokes and centistokes with m²/s. The pound per foot-second conversion uses the high-precision factor 1 lb/(ft·s) ≈ 1.4881639436 Pa·s. Up to 6 significant decimal places are retained, with excess digits automatically truncated.
It supports 10 viscosity units. Dynamic viscosity includes pascal-second (Pa·s), millipascal-second (mPa·s), poise (P), centipoise (cP), kilogram per meter-second (kg/(m·s)), pound per foot-second (lb/(ft·s)), and pound-force second per square foot (lbf·s/ft²); kinematic viscosity includes square meter per second (m²/s), stokes (St), and centistokes (cSt). Enter a value in any unit and the rest of the same type are computed automatically.
No registration or login is required. This tool provides you with free usage every day. Open the page and start using it right away, covering everyday lightweight conversions at zero cost. For higher frequency or larger workloads, you can upgrade to a membership to unlock more quota.
Yes. The page uses a responsive design and works well on mobile, tablet, and desktop browsers. On mobile, simply tap the input field, select a unit, and tap convert to see results, with the same workflow as on desktop.
Because density information is missing. Kinematic viscosity = dynamic viscosity ÷ density (ν = μ / ρ); you need to know the fluid density to convert. Therefore, this tool displays the two categories separately. When you enter a dynamic viscosity unit, only dynamic results are shown, and vice versa.
Click the copy icon to the right of the result field. Each unit result comes with a copy button. Clicking it automatically copies the value to your clipboard, allowing one-click pasting into documents, spreadsheets, or chat windows without selecting text manually.
The lubricant industry often uses kinematic viscosity (cSt) to grade oils. For example, SAE 30 motor oil has a kinematic viscosity of about 9.3~12.5 cSt at 100°C, and ISO VG grades are defined by the cSt value at 40°C. This tool helps you quickly convert between viscosity units for easy oil specification comparison and selection.
Content last updated：2026-08-06
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