Enter the real distance (ft) and the refractive index into the Calculator. The calculator will evaluate the Apparent Distance. 

Apparent Distance Formula

AD = RD / RI


  • AD is the Apparent Distance (ft)
  • RD is the real distance (ft)
  • RI is the refractive index

To calculate the Apparent Distance, divide the real distance by the refractive index.

How to Calculate Apparent Distance?

The following steps outline how to calculate the Apparent Distance.

  1. First, determine the real distance (ft). 
  2. Next, determine the refractive index. 
  3. Next, gather the formula from above = AD = RD / RI.
  4. Finally, calculate the Apparent Distance.
  5. After inserting the variables 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.

real distance (ft) = 4

refractive index = 1.234