Snell’s Law Calculator: Calculate Refraction & Angle Online

This Snell’s Law calculator will help you determine the angle of refraction when a light wave passes between two media with different refractive indices.

Snell’s Law Calculator

This calculator uses Snell’s Law to determine the refraction angle when light passes from one medium to another. Input the indices of refraction of both media and the incidence angle, and click “Calculate” to find the refraction angle.

How to Use the Calculator

  1. Enter the index of refraction for the first medium (n1).
  2. Enter the index of refraction for the second medium (n2).
  3. Input the angle of incidence from the first medium in degrees.
  4. Click the “Calculate” button to compute the refraction angle.

How it Calculates Results

The calculator applies Snell’s Law, which states that n1 * sin(θ1) = n2 * sin(θ2), where θ1 is the angle of incidence and θ2 is the angle of refraction. It converts the input angle to radians before calculation and checks if total internal reflection occurs.


The calculator does not validate the physical possibility of the indices of refraction. It assumes input values are within real-world ranges. If the calculated sine of the refracted angle is greater than 1, it will indicate that total internal reflection occurs, as no real refracted angle exists in this case.

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