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Conversions

Snell's Law Calculator

Variable Legend

n₁= refractive index of medium 1n₂= refractive index of medium 2θ₁= angle of incidence (from normal)θ₂= angle of refraction (from normal)

Snell's law

Angles measured from the normal to the surface.

Solve for refraction angle

Critical angle

Angle beyond which total internal reflection occurs (n₁ > n₂).

Refractive index

Ratio of speed of light in vacuum to speed in medium.

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Pro Tip

Always verify your input values before calculating. For snells law, small input errors can compound and significantly affect the final result.

Difficulty:Intermediate

Did you know?

Diamonds have the highest refractive index of natural gems (2.42) and a critical angle of only 24.4°. Most of the light that enters a diamond undergoes total internal reflection multiple times, creating brilliant sparkle.

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Reviewed May 2026
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