Optical Calculators

Lens Thickness Calculator

Predict how thick a finished lens will be at any point before it's surfaced. Enter the Rx, frame and fit measurements, minimum thickness, base curve and material.

Thickness depends on more than power. Frame size, decentration and material all change where a lens is thickest, and cylinder makes the edge thickness vary around the lens.

Inputs:

  • Lens Rx (sphere, cylinder, axis): plus lenses are thickest in the center, minus lenses at the edge.
  • Frame and fit (eyesize, bridge, effective diameter, PD): these set how far the lens is decentered.
  • Minimum thickness: the edge thickness for plus lenses, or center thickness for minus lenses, that keeps the lens safe and strong.
  • Base curve and material index: higher-index materials make flatter, thinner lenses.

Results:

  • Minimum and maximum edge thickness of the uncut blank
  • Thickness along the horizontal meridian at the nasal and temporal edges
  • Thickness at any angle and distance from center, using the axis inspector

Use it to manage cosmetics, avoid fit problems, and choose the index and base curve that keep the lens light and thin.

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