Snell's Law Angle Calculator — n₁sin θ₁ = n₂sin θ₂

Snell's law bends light at every boundary — air to glass, water to air. Give any three of the four values and find the fourth.

$n_1\sin\theta_1 = n_2\sin\theta_2$

Solve for

Index n₁ (n₁)

Unit

Incident angle (θ₁)

Unit

Index n₂ (n₂)

Unit

Result unit

How to interpret the result

Light hitting water at 45° from air refracts to ~32° — bending toward the normal because water is optically denser.

Angles measured from the normal (not the surface)
If n₁sin θ₁/n₂ exceeds 1, total internal reflection occurs instead (no refracted ray)