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Physics

Diffraction Grating Calculator

Estimate a diffraction maximum angle from wavelength, grating density and order.

SI units shown beside each fieldIdeal model explained below
Physics lab
Physics lab

Use the units beside each input and review the model assumptions.

See the method

Define your system

Runs on your device

Your calculated quantity

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter wavelength, line density, order.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

At normal incidence, sin(θ)=mλ/d, with d=1/(lines per metre).

A WORKED EXAMPLE

Using wavelength = 550 nm, line density = 600 lines/mm, order = 1, the result is 19.2687755 degrees. Change these example inputs to match your task; use the method above to check each step.

Understanding your result

Normal incidence, equal slit spacing and one wavelength. Positive orders are shown; negative orders are symmetric.

What to keep in mind

Normal incidence, equal slit spacing and one wavelength. Positive orders are shown; negative orders are symmetric. An idealized educational model using the stated SI units. Real systems may need additional forces, losses or experimental measurements. Not a safety or equipment specification.

Common questions

How do I use this diffraction grating calculator?

Estimate a diffraction maximum angle from wavelength, grating density and order. Enter wavelength in nm, line density in lines/mm, order. The starting example is editable; use values for the same system or project.

Which assumptions affect this result?

Normal incidence, equal slit spacing and one wavelength. Positive orders are shown; negative orders are symmetric.

Methodology maintained by ClarityKit. How these tools are built and checked.