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Angle of Deviation Calculator

Angle of Deviation Calculator

Enter the angle of incident, the angle of emergence in the tool and the calculator will calculate the angle of deviation.

Angle Of Incidence (I):


Angle Of Emergence (E):


Angle Of Prism (A):


Angle of Deviation Unit :


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The angle of deviation calculator calculates the angle of deviation by the ratio of the angle of incidence and the angle of emergence relative to a prism.

The Angle of Deviation:

The angle of deviation of prisms can be different due to the different materials used in the production of the prisms. The angle of the deviation of a prism is equal to the sum of the angle of incidence and emergence angle minus the angle of the prism. 

The formula for calculating the angle of deviation is:

Angle of Deviation = Angle Of Incidence + Angle of Emergence – Angle of Prism

D = I + E – A

Practical Example:

Consider the angle of the incident (I) is 10 degrees, the angle of emergence (E) is 35 degrees and the prism angle (A) is 35 degrees. Then what is the angle of deviation (D) of the incident ray?


I = 10 degrees

E = 35 degrees

A = 35 degrees

D =?


Now the formula of the angle of deviation is:

D = I + E – A

Now by putting the values in the formula:

D = I + E – A 

D =10 +35 – 35


D= 10

Angle of Deviation = D = 10 degrees

Factors Affecting the Angle of Deviation: 

Factors on which the angle of deviation depends are:

  • The angle of incidence
  • The wavelength of light used
  • The material of the prism 
  • The angle of the prism 

Working of Angle of Deviation Calculator:

Using our calculator needs no effort! Everything is easy to input and you can get straightforward results. Let’s find out how!


  • Enter the angle of incident, angle of emergence, and the angle of the prism
  • Select the unit of the angle of deviation
  • Tap Calculate


  • Angle of deviation
  • Step-by-step calculation


Can the Angle of Deviation be Negative?

Yes, the deviation angle can be negative if the refractive light bends downward. The angle of deviation calculator estimates both the upward and downward refraction angle of deviation.

What is the Maximum Angle of Deviation?

When the angle of incidence is 90 degrees, the maximum deviation occurs. 

Which Color has the Maximum Angle of Deviation?

The Violet light has the maximum deviation as it has the shortest wavelength.


From the source of Wikipedia: Minimum deviation, Formula

From the source of the Angle of deviation, Factors affecting Deviation