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Reading glasses strength is printed as a diopter (D) number with a plus sign, such as +1.00 or +2.50. The American Academy of Ophthalmology (AAO) describes store-bought readers as ranging from +1.00 D to +3.00 D, and a higher number focuses closer. This page lays out the AAO’s published values by viewing distance in one table, explains how to read the label, and describes what ready-made readers are. It is general product information, not medical advice or an eye exam.
Reading glasses strength chart (diopter by task)
| Task or distance | Strength AAO cites | What it means |
|---|---|---|
| Full range of store-bought readers | +1.00 D to +3.00 D | The span AAO gives for readers sold without a prescription |
| Farther viewing distance, such as a music stand | +1.00 D | Lowest end of the range |
| Computer distance | +1.25 D | AAO’s figure for screen distance |
| Near reading, such as a book | +2.25 D to +2.50 D | AAO’s figure for close reading |
| Closer still | +3.00 D | Top of the range |
The computer-distance and near-reading values come from an AAO answer about reading glasses after cataract surgery. They show how strength changes with distance; they are a reference point, not a prescription for any one person.
How to read the chart
Reading glasses diopter chart: what the numbers mean
The “D” stands for diopter, the unit of lens power. The plus sign marks a converging (convex) lens, which is what reading glasses use. The AAO’s rule of thumb is that a higher number is for seeing things closer, and a lower number is for seeing things farther away. So +3.00 D is for closer work than +1.00 D.
Reading glasses sizes and sizes chart
For store-bought readers, the AAO describes the product by its power, so the “size” printed on the label is the diopter number. The AAO describes ready-made readers as one-size-fits-all, which is why frame dimensions are not part of the strength chart above.
Reading glasses magnification chart
The AAO states readers’ strength in diopters. If a package uses another word for strength, compare using the number on the package against the table above in D; do not convert between units yourself.
Ready-made and custom reading glasses
The AAO notes that ready-made readers are one-size-fits-all, cost less than custom glasses and are usually not multifocal. Custom glasses are the made-to-order option, with a different prescription in each eye possible and the pupils aligned to the lens optical centre. The AAO lists lens types as single vision, bifocal, trifocal and progressive.
Check your product’s labelling
Always read the strength printed on the product or its packaging. The chart reports AAO figures and a regulation; it is not a standard for any particular brand or model.
On the regulatory side, the US Code of Federal Regulations defines “magnifying spectacles” (21 CFR 886.5840) as spectacle frames with convex lenses worn by a patient with impaired vision to enlarge images, and classifies them as Class I (general controls). That entry describes that device category only; it is not a strength chart. For how FDA device classes work in general, see FDA medical device classification, 510(k) and PMA. For workplace eyewear, a separate product type, see prescription safety glasses and ANSI Z87.1 and safety glasses side shields.
Common mix-ups
- Higher number, farther view. It is the reverse: the AAO says a higher number is for seeing things closer.
- One strength for every task. The AAO’s own examples differ by distance, from +1.00 D at a music stand to +3.00 D for closer work.
- Size means frame size. On ready-made readers the number on the label is the strength in diopters.
FAQ
What is the usual range of reading glasses strength?
The AAO says store-bought reading glasses range anywhere from +1.00 D to +3.00 D.
What does the number on reading glasses mean?
It is the lens power in diopters (D). The plus sign marks a convex lens, and a higher number is for seeing things closer.
What strengths does the AAO cite for computer distance and near reading?
In its answer about reading glasses after cataract surgery, the AAO cites +1.25 D for computer use and +2.25 to 2.50 D for reading near.
Are reading glasses sold in sizes?
Ready-made readers are described by the AAO as one-size-fits-all and are labelled by their power in diopters.
Sources
All sources checked 2026-10-30.
- American Academy of Ophthalmology, Do I need store-bought or prescription reading glasses after cataract surgery? (checked 2026-10-30).
- American Academy of Ophthalmology, Tips for choosing the right reading glasses (checked 2026-10-30).
- Electronic Code of Federal Regulations, 21 CFR 886.5840 Magnifying spectacles (checked 2026-10-30).
