Mean Free Path Calculator

Calculate mean free path, number density, impingement rate, monolayer formation time, and Knudsen number for any gas at any pressure and temperature.

Input
Kinetic Properties
Mean Free Path λ
50.348m
Number Density n
3.265e+16m⁻³
Mean Speed v̄
464.33m/s
Surface Interactions
Impingement Rate Φ
3.791e+18m⁻²s⁻¹
Monolayer Time τ_ML
Assumes sticking coefficient = 1, n_s = 10¹⁹ m⁻²
2.6381s
Abridged Optics — Mean Free Path Calculator v1.0λ = k_BT/(√2·π·d²·p). Impingement rate: Φ = nv̄/4. Monolayer time: τ = n_s/Φ. Gas data from O'Hanlon [1] and Jousten [2].

All information, equations, and calculations have been compiled and verified to the best of our ability. For mission-critical applications, we recommend independent verification of all values. If you find an error, please let us know.