Snell’s Law Calculator
🔍 Light & optics. Use the Snell’s law formula to find angle in medium 2, n₁, angle in medium 1, n₂: pick the value you want, type the others, and the answer updates as you go.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Angle in medium 2 | ° |
| n₁ | no unit |
| Angle in medium 1 | ° |
| n₂ | no unit |
Worked example
Find the angle in medium 2 when n₁ = 1, Angle in medium 1 = 40 °, n₂ = 1.5.
Using n1sinθ1 = n2sinθ2: Angle in medium 2 = 25.374 °.
Frequently asked questions
What is the formula for Snell’s law?
n1sinθ1 = n2sinθ2.
What do the letters stand for, and what units are used?
Angle in medium 2 in °, n₁, Angle in medium 1 in °, n₂.
How do you calculate angle in medium 2?
Put the values into n1sinθ1 = n2sinθ2. For example, with n₁ = 1, Angle in medium 1 = 40 °, n₂ = 1.5, angle in medium 2 = 25.374 °.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (angle in medium 2, n₁, angle in medium 1, n₂) and fill in the others: it rearranges the formula for you.
