Enter the angle of incidence into the calculator to determine the angle of reflection.

Law of Reflection Formula

The following formula is used to calculate the angle of reflection based on the Law of Reflection.

θr = θi


  • θr is the angle of reflection (degrees)
  • θi is the angle of incidence (degrees)

To calculate the angle of reflection, simply take the angle of incidence. According to the Law of Reflection, these two angles are always equal. This means that if a ray of light (or any other type of wave) hits a surface at a certain angle, it will reflect off the surface at the same angle, but on the opposite side of the normal line.

What is the Law of Reflection?

The Law of Reflection is a principle in physics that states that the angle of incidence is equal to the angle of reflection. This means that when a ray of light hits a smooth surface, such as a mirror, it will bounce off at the same angle as it hit the surface, but on the opposite side of the normal line (a line perpendicular to the surface at the point of incidence). This law applies to all types of waves, including light, sound, and water waves.

How to Calculate Law of Reflection?

The following steps outline how to calculate the Law of Reflection using the formula θr = θi.

  1. First, determine the angle of incidence (θi) in degrees.
  2. Next, use the formula θr = θi to calculate the angle of reflection (θr) in degrees.
  3. Finally, calculate the Law of Reflection.
  4. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Angle of incidence (θi) = 30 degrees