Free tools for optical shops

Two calculators for the sums an optical counter does every day. They are free, need no sign-up, and run in your browser. Nothing you type is sent anywhere.

• Lens transposition calculator

  Convert a prescription between minus and plus cylinder. Type SPH, CYL and axis and get the transposed form, checked against the limits a prescription allows.

• Spectacle GST calculator

  GST on frames, lenses, contact lenses, sunglasses, cases and repairs. Handles discounts, tag prices that already include GST, IGST and the Bill of Supply.

For longer reads, see the guides for optical shop owners.