Refractive Index of Air Calculator

Calculate the refractive index of air using the modified Edlén equation (Birch & Downs 1994) with humidity correction. Accounts for wavelength, temperature, pressure, humidity, and CO₂.

Input
Refractive Index
n (air)
Modified Edlén (Birch & Downs 1994)
1.00027146
Refractivity (n−1)×10⁸
27146.2
Wavelength in Air
λ_air
λ_vac / n
632.6283nm
OPL correction
(n − 1) per meter of air path
271462nm/m
Contribution Breakdown (×10⁸)
Dispersion (std. air)
Peck & Reeder
27653.4
CO₂ correction
Δ from 450 ppm
0
Humidity correction
f = 933.0 Pa
-3.391e+1
Abridged Optics — Refractive Index of Air Calculator v1.0Modified Edlén (Birch & Downs 1994) · Peck & Reeder dispersion · Sonntag 1990 water vapor · Valid 300–1700 nm

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.