Eyewear, Lenses & Vision Products worked example

Lens Blank Yield at 69% target first-pass blank yield: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop target first-pass blank yield to 69%, then walk the calculation through step by step. Calculate first-pass yield from usable lens blanks compared with blanks issued to production.

The inputs for this scenario

  • Usable lens blanks after processing: 930 blanks (held at the documented default)
  • Lens blanks issued to production: 1,000 blanks (held at the documented default)
  • Target first-pass blank yield: 69 % (the input this scenario stresses; the baseline uses 96)

Working through the calculation

  • The calculation starts from the formula this tool documents: Lens blank yield = usable lens blanks after processing ÷ lens blanks issued to production × 100.
  • Lens blank yield works out to 93 % at these inputs, and this is the headline figure for the scenario.
  • Yield shortfall to target works out to -24 points at these inputs.
  • Usable lens blanks after processing works out to 930 blanks at these inputs.
  • Lens blanks issued to production works out to 1,000 blanks at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where target first-pass blank yield sits at 96% and the headline result is 93 %, this scenario lands almost exactly on the baseline at 93 %.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to target first-pass blank yield, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It's a single ratio over a chosen window; it won't tell you which step (generating, polishing, coating) caused the loss — pair it with defect-by-stage tracking for root cause.

Results at a glance

  • Lens blank yield: 93 % (headline result)
  • Yield shortfall to target: -24 points
  • Usable lens blanks after processing: 930 blanks
  • Lens blanks issued to production: 1,000 blanks

Run it with your numbers

  • To rerun this with your own numbers, open the live Lens Blank Yield calculator, set target first-pass blank yield to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.