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Kinematic Viscosity Converter

Convert fluid viscosity relative to density across square meters per second (m²/s), Stokes (St), Centistokes (cSt), and ft²/s with real-time bidirectional calculations.

Explore Kinematic Viscosity Guide & Formulas↓View Kinematic Viscosity Converter Chart→

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Popular Kinematic Viscosity Conversion Shortcuts

Instant pair conversions with verified scientific and mathematical formulas

Quick Pairs

cSt to m²/s→

1,000,000 cSt = 1 m²/s

m²/s to cSt→

1 m²/s = 1,000,000 cSt

1 m²/s = 10,000 Stokes

Stokes to m²/s→

1 Stoke = 0.0001 m²/s

cSt to ft²/s→

100,000 cSt = 0.1076 ft²/s

ft²/s to cSt→

1 ft²/s = 92,903 cSt

Kinematic Viscosity Reference Equivalents (1 Square meter per second)

Standard ratios measured against the base Square meter per second (m²/s)

Reference Table

Unit Name	Symbol	Equivalent in 1 m²/s	Quick Pair Page
Square meter per second	m²/s	1 m²/s = 1 m²/s	Base Unit
Stoke	St	1 m²/s = 10,000 St	m²/s to St →
Centistoke	cSt	1 m²/s = 1,000,000 cSt	m²/s to cSt →
Square foot per second	ft²/s	1 m²/s = 10.76391 ft²/s	m²/s to ft²/s →

ISO Viscosity Grades & Kinematic Viscosity Reference Chart

Lookup table of standard ISO VG lubrication oil grades and common fluids measured in Centistokes (cSt) at 40°C

Lookup Matrix

Fluid / Lubricant Grade	Centistokes (cSt @ 40°C)	m²/s (SI)	Stokes (St)	ft²/s
Water (Pure, 20°C)	1.00 cSt	0.0000010 m²/s	0.0100 St	0.0000108 ft²/s
Kerosene / Diesel Fuel (20°C)	2.50 cSt	0.0000025 m²/s	0.0250 St	0.0000269 ft²/s
ISO VG 10 (Spindle Oil)	10.0 cSt	0.0000100 m²/s	0.1000 St	0.0001076 ft²/s
ISO VG 22 (Light Hydraulic)	22.0 cSt	0.0000220 m²/s	0.2200 St	0.0002368 ft²/s
ISO VG 32 (Standard Hydraulic Oil)	32.0 cSt	0.0000320 m²/s	0.3200 St	0.0003444 ft²/s
ISO VG 46 (Industrial Compressor)	46.0 cSt	0.0000460 m²/s	0.4600 St	0.0004951 ft²/s
ISO VG 68 (Machine Tool Way Lube)	68.0 cSt	0.0000680 m²/s	0.6800 St	0.0007319 ft²/s
SAE 10W-30 Motor Oil (@ 40°C)	70.0 cSt	0.0000700 m²/s	0.7000 St	0.0007535 ft²/s
ISO VG 100 (Reciprocating Compressor)	100.0 cSt	0.0001000 m²/s	1.0000 St	0.0010764 ft²/s
ISO VG 220 (Enclosed Gear Oil)	220.0 cSt	0.0002200 m²/s	2.2000 St	0.0023681 ft²/s
ISO VG 460 (Heavy Industrial Gear)	460.0 cSt	0.0004600 m²/s	4.6000 St	0.0049514 ft²/s
SAE 85W-140 Hypoid Axle Gear Oil	400.0 cSt	0.0004000 m²/s	4.0000 St	0.0043056 ft²/s

Tribology & Lubrication Engineering

Kinematic Viscosity: Capillary Viscometry, ISO VG Grades & Tribological Standards

Authoritative guide to kinematic fluid flow, Ubbelohde capillary viscometers, ISO viscosity grades, and conversion formulas across mechanical lubrication systems.

Physical Definition & Momentum Diffusivity

Kinematic viscosity ν represents a fluid's momentum diffusivity—the rate at which momentum diffuses through a fluid layer relative to its inertia:

ν = μ / ρ

Kinematic Viscosity Formula (ν = m²/s, μ = Dynamic Viscosity in Pa·s, ρ = Density in kg/m³)

Unlike dynamic viscosity, which characterizes fluid shear resistance under forced external pressure, kinematic viscosity quantifies how rapidly a fluid flows when motivated purely by its own gravitational hydrostatic head (gravity flow).

Centistokes (cSt) and mm²/s Equivalence

The fundamental relationship between the metric CGS Stoke and the SI system yields an exceptionally convenient identity:

1 Centistoke (cSt) = 1 mm²/s

Because 1 Stoke = 1 cm²/s = 10⁻⁴ m²/s, dividing by 100 gives 1 cSt = 10⁻⁶ m²/s = 1 mm²/s. Tribologists and lubrication engineers treat cSt and mm²/s as completely interchangeable.

ISO 3448 Viscosity Grades (ISO VG)

The International Organization for Standardization specifies industrial lubricants by their midpoint kinematic viscosity in cSt at 40°C: ISO VG 32, ISO VG 46, ISO VG 68, and ISO VG 220.

Viscosity Index (VI) & Thermal Thinning

The Viscosity Index (VI) measures how drastically an oil's kinematic viscosity changes between 40°C and 100°C. Lubricants with high Viscosity Indices (VI > 140, typical of full synthetics with polymer VI improvers) resist excessive thinning at high temperatures while remaining sufficiently fluid for cold startup circulation.

About Kinematic Viscosity Units & Formulas

1 m²/s = 10,000 Stokes = 1,000,000 Centistokes (cSt).

Square meter per secondm²/s

SI kinematic viscosity unit

StokeSt

CGS unit (10⁻⁴ m²/s)

CentistokecSt

Engine oil grade specification unit (10⁻⁶ m²/s)

Square foot per secondft²/s

Imperial kinematic viscosity

FREQUENTLY ASKED QUESTIONS

Kinematic Viscosity Converter FAQs

Frequently asked questions regarding kinematic viscosity conversion metrics, formulas, and real-world calculation standards

How do you convert Centistokes (cSt) to m²/s?

To convert Centistokes (cSt) to square meters per second (m²/s), multiply by 10⁻⁶ (0.000001) or divide by 1,000,000: m²/s = cSt × 10⁻⁶.

Example: A standard hydraulic oil rated at ISO VG 46 has a kinematic viscosity of 46 cSt at 40°C: 46 × 10⁻⁶ = 0.000046 m²/s.

Reverse Conversion: Multiply m²/s by 1,000,000 to obtain Centistokes (0.0001 m²/s × 1,000,000 = 100 cSt).

What is kinematic viscosity in fluid mechanics?

Kinematic viscosity (ν, nu) is the ratio of dynamic (shear) viscosity (μ) to the density of the fluid (ρ):

ν = μ / ρ

It represents a fluid's resistance to gravity-driven flow (such as draining through a calibrated capillary tube or gravity viscometer). In the SI system, it has dimensions of Area / Time, measured in m²/s.

What is the relationship between Centistokes (cSt) and Stokes (St)?

The Stoke (St) is the CGS unit of kinematic viscosity (named after Sir George Gabriel Stokes), defined as 1 cm²/s = 10⁻⁴ m²/s.

1 Centistoke (cSt) is one-hundredth of a Stoke (1 cSt = 0.01 St = 1 mm²/s = 10⁻⁶ m²/s). Because 1 cSt equals exactly 1 mm²/s, Centistokes is the worldwide engineering standard for motor oils, lubricants, and hydraulic fluids.

How do you calculate dynamic viscosity from kinematic viscosity?

To find dynamic viscosity (μ in cP or Pa·s), multiply kinematic viscosity (ν in cSt) by the fluid's mass density (ρ in g/cm³):

μ (cP) = ν (cSt) × ρ (g/cm³)

Example: An engine oil has a kinematic viscosity of 100 cSt and a density of 0.88 g/cm³ (880 kg/m³). Its dynamic viscosity is: 100 × 0.88 = 88 cP (0.088 Pa·s).

Why do engine oil grades (like 5W-30) specify viscosity in cSt?

SAE J300 automotive oil standards and ISO VG industrial specifications define viscosity grades in Centistokes (cSt) at standardized test temperatures (usually 40°C and 100°C). In a "5W-30" multi-grade oil, the "5W" specifies low-temperature pumping viscosity (measured in cold crank simulators), while the "30" guarantees that kinematic viscosity remains safely between 9.3 and 12.5 cSt at engine operating temperature (100°C) to prevent metal-on-metal bearing wear.