How to Choose the Right Reading Glasses Strength
A Practical Guide for Optical Retailers and Bulk Buyers
If you are sourcing reading glasses for your store or business, one question comes up more than any other: What strength do my customers actually need?
Getting the answer right matters. Hand a customer the wrong power, and they will blame the product—not their own guesswork. Hand them the right power, and they will come back for more.
Here is a straightforward, field tested way to understand reading glass strengths.
The Simple Rule: Start with Age, Then Adjust
Most people begin needing reading help between 40 and 50. The table below gives you a reliable starting point for an average customer with healthy eyes and no major distance prescription.
| Age Range | Starting Strength |
| 40 – 44 | +1.00 to +1.25 |
| 45 – 49 | +1.50 to +1.75 |
| 50 – 54 | +2.00 |
| 55 – 59 | +2.25 to +2.50 |
| 60 – 64 | +2.75 to +3.00 |
| 65+ | +3.00 to +3.50 |
Important: This is a starting point, not a final answer.
The Two Step Test You Can Do Anywhere
You do not need expensive equipment to confirm the right strength. If you have a newspaper, a phone screen, or a product label, you have everything you need.
Step 1 – Find the "Too Weak" Line
Ask your customer to hold reading material at their normal reading distance (usually 14–16 inches / 35–40 cm).
Start with a lower strength, like +1.00. Slowly go up.
If the text stays blurry or they keep moving the page further away to see clearly → the glass is too weak.
Step 2 – Find the "Too Strong" Line
Keep increasing the power until the text becomes sharp and comfortable.
Then go one step higher.
When the text is sharp but the customer starts feeling eye strain or needs to hold the page closer than normal → the glass is too strong.
The right strength is the lowest one that makes the text clear at a comfortable reading distance.
Common Mistakes Retailers See (and How to Avoid Them)
| Mistake | Why It Happens | What to Do Instead |
| Choosing the strongest possible lens | People think "stronger = better" for reading | Explain that too much power causes headaches and shorter reading distance |
| Buying single strength for everyone | Easier for stock management | Carry a range from +1.00 to +3.50. Most sales cluster around +1.50 to +2.50 |
| No test available in store | Customers guess and often get it wrong | Keep a simple diopter tester or a few sample glasses on hand |
| Ignoring existing distance prescriptions | Uncorrected nearsightedness changes reading needs | For customers who wear glasses for distance, reading needs become more complex — let them ask their eye doctor for an exact ADD number |
A Special Note for Bulk Buyers
If you are stocking reading glasses for retail:
Best selling powers are usually +1.50, +2.00, and +2.50. These three strengths can cover roughly 70% of casual buyers.
Full range suggestion: Stock +1.00 to +3.50 in 0.25 steps for optical stores. For general retail (drugstores, gift shops, online marketplaces), 0.50 steps (+1.00, +1.50, +2.00, +2.50, +3.00) are often enough.
Packaging tip: A clear power label on the temple or box reduces returns and customer confusion.
When a Reading Glass Is Not Enough
Not everyone fits the simple age based rule. Some customers need professional prescription glasses because:
They already wear glasses for distance (nearsighted or farsighted)
Their two eyes need different strengths
They need astigmatism correction
In these cases, standard reading glasses will not work well. Do not try to fit them with an off the shelf product. Instead, recommend an eye exam.
A customer who gets the right solution — even if it is not your product — will remember your honesty.
Quick Summary for Your Sales Staff
| Customer Profile | Recommended Action |
| Age 40–50, healthy eyes | Try +1.00 to +1.50 |
| Age 50–60, healthy eyes | Try +1.75 to +2.25 |
| Age 60+, healthy eyes | Try +2.50 to +3.00 |
| Already wears distance glasses | Recommend eye exam for exact ADD |
| Complains of headache or strain after reading | Strength may be too high |
| Holds phone/paper at arm's length | Strength is too low |
Final thought: The best reading glass is not the strongest one. It is the one your customer forgets they are wearing.
When their eyes feel relaxed and the text stays sharp page after page — that is when you know you have chosen the right strength.
