Gaussian Beam Calculator
Calculate Gaussian beam propagation parameters — Rayleigh range, divergence, beam radius, and beam quality.
Most laser beams are well approximated by a Gaussian TEM₀₀ mode, characterized by a waist radius w₀, wavelength λ, and beam quality factor M². Given these inputs, the Gaussian beam equations fully determine how the beam evolves with propagation distance: the Rayleigh range (depth of focus), divergence half-angle, beam radius at any distance, and peak irradiance. This calculator also accepts non-ideal beams via the M² parameter — an M² of 1.0 is a perfect Gaussian; real beams have M² > 1. Use this tool when designing beam delivery optics, calculating focused spot size, or setting up fiber coupling.
Beam Parameters
Enter beam waist radius and wavelength to see results.
Abridged Optics — Gaussian Beam Calculator v1.0z_R = πw₀²/(M²λ) · θ = M²λ/(πw₀) · w(z) = w₀√(1+(z/z_R)²)