🔦 Single Slit Diffraction Calculator
Calculate where dark fringes (minima) appear when light diffracts through a single narrow slit.
nm
µm
m
What single-slit diffraction is
When light passes through a narrow slit, it spreads out and forms a pattern of bright and dark bands on a distant screen. This calculator finds the angle (and screen position) of the dark fringes, called minima.
The formula
Minima occur where a·sin(θ) = mλ, where a is the slit width, λ is the wavelength of light, m is the order of the minimum (1, 2, 3…), and θ is the diffraction angle measured from the center. If the slit is narrow enough that mλ/a exceeds 1, that order of minimum does not physically occur.
This tool is intended for general physics education and reference.
Last reviewed August 2026