Tool · Estimator · 6 questions
Reading-glasses strength estimator
Six short questions, including a calibrated arm’s-length test, calibrated against the AAO presbyopia age table. Returns a diopter range you can use to skip the “+2.00 grab from the drugstore” mistake. An estimator, not a prescription.
Last reviewed: July 2026
What this tool helps with
- Picking off-the-shelf reader strength — OTC readers come in fixed 0.25 D steps. We narrow the right step.
- Preventing the +2.00 grab — most first-time buyers reach for too strong a reader and end up with another pair on a shelf.
- Identifying when readers aren’t the answer — if you have distance Rx or progressives, this tool routes you to an eye exam instead.
- A printable diopter chart to bring to your next eye exam (delivered by email).
An estimator, not a prescription
We map your answers through a rule-based table calibrated against the AAO Refractive Errors Preferred Practice Pattern. We can estimate a reasonable diopter range — but real prescriptions account for astigmatism, vergence, and binocular balance that self-reported answers can’t measure. The AOA recommends a comprehensive eye exam every two years after age 40.
Read the full methodology for the rules behind the estimate.