Matter Wavelength Calculator

About this calculator

The matter wavelength, or de Broglie wavelength, expresses the wave-like nature of any moving particle: λ = h / (m·v) = h / p, where h is Planck's constant, m is the particle's mass, v is its velocity and p is its momentum. Proposed by Louis de Broglie in 1924, the idea extended the wave-particle duality already known for light to all matter — electrons, atoms, even large molecules all have an associated wavelength, though it's only measurable for very light, fast-moving particles because h is so tiny.

This calculator finds λ from a particle's mass and velocity. Physicists and chemistry students use the de Broglie wavelength to understand electron diffraction (the basis of electron microscopy, which achieves far finer resolution than light microscopy because electrons have much shorter wavelengths), to explain quantization in atomic orbitals via standing-wave conditions, and to interpret experiments like the Davisson–Germer experiment that confirmed matter waves exist.