Dynamic to Kinematic Viscosity Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/9/2026
Kinematic viscosity is calculated with ν = µ ÷ ρ, where µ is the dynamic viscosity and ρ the fluid's density. For air at room temperature (µ≈1.81×10⁻⁵ Pa·s, ρ≈1.225 kg/m³), the kinematic viscosity is about 1.48×10⁻⁵ m²/s.
Explanation
Dynamic viscosity (µ, expressed in pascal-seconds) measures a fluid's intrinsic resistance to flow — it's the quantity most often given directly on an industrial fluid's technical data sheet. Kinematic viscosity (ν, expressed in m²/s) is derived from it by relating it to the fluid's density, which makes it a measure of how momentum diffuses within the fluid, independent of its density. This distinction isn't just a formality: nearly all the dimensionless fluid mechanics numbers published on this site — our Reynolds number calculator, our Schmidt number calculator, and the other numbers in this family — use KINEMATIC viscosity in their formula, whereas industrial fluid technical sheets (oils, lubricants, chemicals) almost always give DYNAMIC viscosity. This calculator therefore serves as a practical bridge between the data available on a technical sheet and what these formulas actually expect. A striking example of this distinction: although air is about 55 times less viscous (dynamically) than water, its KINEMATIC viscosity is actually higher than water's, simply because air is about 800 times less dense — it's kinematic viscosity, not dynamic, that directly determines the flow regime (laminar or turbulent) via the Reynolds number.
Example: air's kinematic viscosity
Inputs
Air's dynamic viscosity: 1.81×10⁻⁵ Pa·s. Density: 1.225 kg/m³.
Calculation
ν = (1.81×10⁻⁵) ÷ 1.225 ≈ 1.4776×10⁻⁵ m²/s.
Result
Air's kinematic viscosity at room temperature is about 1.48×10⁻⁵ m²/s, the value commonly used in fluid mechanics calculations.
Frequently asked questions
Why do two different measures of viscosity exist?
Because they serve different needs: dynamic viscosity directly characterizes the fluid's internal resistance to deformation (useful for calculating a viscous friction force), while kinematic viscosity, by incorporating density, instead describes how motion propagates through the fluid — the relevant quantity for characterizing a flow regime, regardless of the fluid's density.
Does air really have a higher kinematic viscosity than water?
Yes, and it's often counterintuitive: although water is much more viscous "to the touch" (far higher dynamic viscosity), its very high density relative to air pulls its kinematic viscosity below that of air. Concretely, this means the same Reynolds number (and therefore the same flow regime, laminar or turbulent) is reached at very different speeds in air and in water, for the same geometry.
Does viscosity change with temperature?
Yes, strongly, and in opposite directions depending on the state of matter: a liquid's viscosity generally decreases as temperature rises (warm honey flows more easily than cold honey), while a gas's viscosity increases slightly with temperature. The values entered in this calculator should therefore match the actual temperature of the fluid being studied, not a generic value.