Optical Calculators

Single Vision Blank Size Calculator

Find the smallest lens blank that will cut out for a frame. Enter the PD, eyesize, bridge and effective diameter.

A lens blank starts as a circle. Because a patient's pupils rarely line up with the center of the frame openings, the lens is usually decentered when it's cut. If the blank is too small, it won't fill the frame once it's shifted.

Inputs:

  • Interpupillary distance (PD)
  • Frame eyesize (A measurement): the width of the lens opening.
  • Frame bridge (DBL): the distance between the lens openings.
  • Effective diameter (ED): twice the distance from the center of the opening to its farthest edge.

The calculator works out the decentration and gives the Minimum Blank Size (MBS) in millimeters, so you can order the right blank and avoid wasted lenses.

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