De Broglie λ

λ = h / (mv) for non-relativistic momentum.

Mass (kg)

v (m/s)

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λ (m)

0.000000001455

λ (nm)1.454681

How to Use This Calculator

Enter the particle mass in kg (electron = 9.109e-31 kg, proton = 1.673e-27 kg).
Enter the particle velocity in m/s (must be significantly less than the speed of light for classical de Broglie).
Review the calculated de Broglie wavelength in meters and nanometers.
Compare wavelength to atomic scale (~0.1 nm) to assess whether wave behavior is significant.
For relativistic particles, use the relativistic momentum p = gamma*m*v instead.

What each input means

Mass (kg): Electron ~9.11e-31.
v (m/s): Particle velocity in meters per second. Must be non-relativistic (much less than c) for this formula.

λ = h / (m × v) — de Broglie wavelength from Planck's constant, mass, and velocity

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