Convert kinematic viscosity units — m²/s, Stokes, centistokes, ft²/s and more.
| Unit | Name | Value |
|---|---|---|
| m²/s | Square Meter/Second | 0.00064516 |
| cm²/s | Square Centimeter/Second | 6.4516 |
| St | Stokes | 6.4516 |
| cSt | Centistokes | 645.16 |
| ft²/s | Square Foot/Second | 0.0069444474 |
Formula: Stokes = in²/s × 6.452
Multiply any in²/s value by 6.452 to get Stokes.
Reverse: in²/s = Stokes × 0.155
Water reference (20°C): 0.001556 in²/s = 0.01004 St
Values at ~20°C unless noted. Factor: 1 in²/s = 6.452 St
| in²/s (in²/s) | Stokes (St) | Fluid |
|---|---|---|
| 2.325e-05 in²/s | 0.00015 St | Air (20°C) |
| 0.000775 in²/s | 0.005 St | Petrol (gasoline) |
| 0.001556 in²/s | 0.01004 St | Water (20°C) |
| 0.002325 in²/s | 0.015 St | Ethanol |
| 0.00465 in²/s | 0.03 St | Diesel fuel |
| 0.05425 in²/s | 0.35 St | SAE 10W motor oil |
| 0.1302 in²/s | 0.84 St | Olive oil |
| 0.155 in²/s | 1 St | SAE 30 motor oil |
| 0.279 in²/s | 1.8 St | SAE 90 gear oil |
| 2.186 in²/s | 14.1 St | Glycerin (20°C) |
| 7.75 in²/s | 50 St | Honey |
| 12.4 in²/s | 80 St | Molasses |
| 77.5 in²/s | 500 St | Tomato ketchup |
| 387.5 in²/s | 2500 St | Peanut butter |
| 1.550e+18 in²/s | 1.000e+19 St | Glass (room temp) |
1 in²/s = 6.452 St.
Water at 20°C = 1 cSt = 0.01 St = 10⁻⁶ m²/s. Use as reference.
Multiply result by 0.155 to recover the original in²/s value.
Specifies lubricant viscosity grades in cSt at 40°C and 100°C per ISO VG and SAE standards.
Uses kinematic viscosity in cSt for pipeline flow calculations, pump sizing, and heat exchanger design.
Measures crude oil and refined product viscosity in cSt for pipeline transport and refinery design.
Selects hydraulic fluids based on kinematic viscosity in cSt for pump compatibility and system efficiency.
Characterizes food product viscosity (honey, sauces, oils) in cSt for process design and quality control.
Uses ft²/s or cSt for atmospheric kinematic viscosity in Reynolds number calculations for aircraft design.
Square inch per second (in²/s) is occasionally used in US precision engineering and hydraulic system specifications where inch-based units are standard. One in²/s = 6.4516×10⁻⁴ m²/s = 6.4516 St.
In²/s appears in some US hydraulic fluid specifications and industrial machinery manuals. A typical hydraulic fluid at 40°C might be specified as 0.04 in²/s (40 cSt). It is rarely used in modern practice compared to cSt.
Interesting fact: Hydraulic systems in US aircraft were historically specified using in²/s for fluid viscosity, alongside psi for pressure and gpm for flow — a fully inch-pound unit system that required separate conversion when integrating with metric components.
The Stokes (St) is the CGS unit of kinematic viscosity, equal to exactly 1 cm²/s = 10⁻⁴ m²/s. It was named after Sir George Gabriel Stokes by the British Association for the Advancement of Science in 1882.
The Stokes is used in petroleum engineering and some industrial viscometer specifications. Water at 20°C = 0.01 St = 1 cSt. Engine oils range from 50–200 cSt (0.5–2 St) at 40°C. Pourable molasses is about 5–10 St (500–1,000 cSt).
Interesting fact: George Stokes was also the first to explain fluorescence (Stokes shift), derive the Navier-Stokes equations of fluid motion, and develop the theory of diffraction. His work in fluid mechanics in the 1840s–1850s remains fundamental to modern engineering.
Kinematic viscosity (ν = μ/ρ) measures how a fluid flows under gravity. The cSt is dominant in industry; m²/s is the SI unit; St and cm²/s are the CGS equivalents. Key anchor: water at 20°C ≈ 1 cSt = 10⁻⁶ m²/s = 0.01 St.
Exact factor: 1 in²/s = 6.452 St. Reverse: 1 St = 0.155 in²/s.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.