Snell's Law Refraction Calculator
Angle of refraction between two media.
Enter your values
ⓘ Live results
Results
- Angle of refraction
- 22.08 degrees
- sin(theta2)
- 0.3759
Quick answer
n1 sin(theta1) = n2 sin(theta2).
n1 sin(theta1) = n2 sin(theta2)
How to use the Snell's Law Refraction Calculator
- 1Enter the refractive indices of the two media (e.g. air = 1.0, water = 1.33, glass ~1.5).
- 2Enter the angle of incidence measured from the normal.
- 3Read the angle of refraction, or check for total internal reflection.
Worked example
Using the values the calculator loads with:
Inputs
- Refractive index 11.0
- Refractive index 21.33
- Angle of incidence30 degrees
Results
- Angle of refraction22.08 degrees
- sin(theta2)0.3759
Frequently asked questions
What is total internal reflection?
It happens going from a denser to a less dense medium beyond the critical angle — no light refracts out.
Why does a straw look bent in water?
Light refracts at the water surface, shifting the apparent position of the submerged part.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.