Snell's Law Calculator

How to use it

1. N₁ = 1.0 (air), θ₁ = 45°, nâ‚‚ = 1.5 (glass)
2. Calculate without(45°) ≈ 0.7071
3. Apply Snell's law: without(θ₂) = (1.0 × 0.7071) ÷ 1.5 = 0.4714
4. Find θ₂ = arcsin(0.4714) ≈ 28.1255°

Common mistakes

• ⚠️ Using degre is in sine function without radian conversion
• ⚠️ Not checking for total internal reflection condition
• ⚠️ Swapping n1 and n2 in the formula

Worked example

Calculate refraction from air (n=1) to water (n=1.33) at 30 deg.

The refraction angle {theta2} degre is is the angle of the light ray in the second medium.

Input guide