What is kinematic viscosity?
Kinematic viscosity describes how a fluid’s internal friction (viscosity) relates to its density, and it governs how air behaves in situations like boundary layers, drag, and flow through ducts.
The formula
Dynamic viscosity of air is estimated with Sutherland’s formula: μ = μref × (T/Tref)1.5 × (Tref + C) ÷ (T + C), using reference viscosity 1.716 × 10-5 Pa·s at 273.15 K and Sutherland’s constant C = 110.4 K for air. Air density is found from the ideal gas law, ρ = P ÷ (Rspecific × T), with Rspecific = 287.05 J/(kg·K). Kinematic viscosity is then ν = μ ÷ ρ.
This treats air as an ideal gas, which is accurate for typical atmospheric conditions but less so at very high pressures or extreme temperatures. This calculator is for general fluid mechanics and engineering education.