Snell's Law Refraction Calculator
Angle of refraction between two media.
Enter your values
Enter the refractive index 1 you are working with.
Enter the refractive index 2 you are working with.
Enter the angle of incidence in degrees.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Angle of refraction
- 22.08 degrees
- sin(theta2)
- 0.3759
Quick answer
n1 sin(theta1) = n2 sin(theta2).
n1 sin(theta1) = n2 sin(theta2)
At a glance
| What it does | Angle of refraction between two media. |
|---|---|
| Category | Physics |
| Inputs needed | Refractive index 1, Refractive index 2, Angle of incidence |
| Main output | Angle of refraction |
| Formula | n1 sin(theta1) = n2 sin(theta2) |
| Cost | Free — no sign-up, no download |
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.
Inputs explained
- Refractive index 1
- Enter the refractive index 1 you are working with.
- Refractive index 2
- Enter the refractive index 2 you are working with.
- Angle of incidence(degrees)
- Enter the angle of incidence in degrees.
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.
What do I need to enter into the Snell's Law Refraction Calculator?
Just 3 values: refractive index 1, refractive index 2, angle of incidence. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Snell's Law Refraction Calculator work out the answer?
n1 sin(theta1) = n2 sin(theta2). It applies the formula n1 sin(theta1) = n2 sin(theta2) and shows the working so you can check each step by hand.
Is the Snell's Law Refraction Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.