Sunglasses Rx: Which Numbers Belong in Your Sun Pair
Picking a tint is the easy part. What decides how a sun pair actually works is which version of your Rx goes into the lenses, and whether those numbers are still current.
Most people shopping for Sunglasses Rx spend their time on frame shape and lens color. Fair enough; those are the fun parts. But when a sun pair disappoints, it usually isn't the color. It's that the lenses were built from the wrong version of the wearer's Rx, or from numbers that had quietly gone stale.
An eyeglass prescription isn't one number. It can describe distance vision, close-up vision or both, and plenty of people own glasses built for a single job. Which of those your sunglasses copy decides whether you can read a menu on a patio, catch a highway exit sign early, or do neither particularly well.
For most people, Sunglasses Rx use the same distance numbers as their everyday glasses. Change that only when your Rx includes an ADD (reading) power, when your everyday glasses are a computer or reading pair, or when you mainly wear contacts. In those cases, choose the numbers by what you need to see sharply outdoors.
Start hereYour Rx Is a Set of Instructions, Not a Single Number
The slip from your last eye exam usually shows a small grid with a row for each eye: OD for the right eye, OS for the left. Four kinds of numbers can appear on it.
Sphere, the main focusing power. A minus sign means distance is blurry without glasses; a plus sign means close-up is the harder job.
Cylinder, the strength of astigmatism correction. Skip it and some lines look soft or slightly stretched.
The angle, from 1 to 180, at which the cylinder power sits. It only matters when there is a CYL value.
Extra power for close-up work, usually showing up in your 40s. This is the line that makes the sun pair decision interesting.
Three things tend to go wrong when these numbers move into a sun pair:
- Copying the wrong pair. If your everyday glasses were made for a desk, their numbers are tuned for a screen at arm's length, not a road or a shoreline. People forget this more often than you'd think, because a computer pair can feel like an everyday pair indoors.
- Copying contacts. A contact lens prescription is not a glasses prescription. Contacts sit on the eye; glasses sit roughly half an inch in front of it, and beyond about ±4.00 that gap changes the power you need. Contact prescriptions also list a base curve and diameter, which mean nothing to a sunglass lens.
- Copying old numbers. It's tempting to order from the slip you have, even if it's two summers old. Dark lenses make that riskier than it is with clear ones, for reasons covered in the Squint Clue below.
The decisionThe Sun Script: Match the Numbers to What You Read Outdoors
The Sun Script comes down to one question: what do you need to see sharply while it's bright out? Not what you look at all day. Only the sunny part. Answer it honestly, then find the row that sounds like you.
The Sun Script: which numbers go into your Sunglasses Rx
| If this sounds like you | Put this in your Sunglasses Rx | What you give up |
|---|---|---|
| No ADD on your slip, and outdoors you mostly look far: driving, trails, the bleachers | Your full distance Rx, including CYL and AXIS | Nothing, as long as the numbers are current |
| You have an ADD, but sunny time is mostly far away: a long drive, a day on the lake, a ballgame | Distance-only lenses (one power, no reading area) | Close reading. You'll peek under the frame or lift it to read your phone |
| You have an ADD and read outside a lot: patio menus, phone maps, a scorecard, a fishing knot | Distance plus ADD, as a progressive or lined bifocal lens | Width. Each sharp zone is narrower, so you aim with your head more |
| Distance is fine without glasses; only up close is blurry | Sun readers: no power up top, reading power only in the lower part | Very little. Avoid full-lens reading power in a sun pair: everything past arm's length will blur |
| Your everyday glasses are a computer or office pair | Your full distance Rx, not the computer numbers | Nothing. The computer pair stays at your desk |
| You wear contacts most days | Your current glasses Rx, so the pair doubles as your backup | A second pair to keep track of on contact days |
| Your Rx is tiny: SPH −0.25 or −0.50, no CYL | Maybe nothing yet. Run the Squint Clue first | Possibly a little crispness on distant signs |
Stuck between rows two and three? Picture the reading area simply missing. If your honest reaction is "I'd just lift my glasses for a second," go distance-only and enjoy the wider clear view. If it's "I'd be stuck," build the ADD in. Golfers, anglers and anyone who navigates by phone on foot usually land in row three; road-trippers and boaters often prefer row two.
Contact lens wearers get more out of Sunglasses Rx than they expect. The FDA advises keeping contact lenses away from water, including pools, lakes and the ocean, so a beach day is exactly when you'd want sharp vision without them. Eye care groups also commonly suggest keeping a current pair of glasses as a backup. Making that backup a sun pair means it actually leaves the drawer.
Once you know your row, pick a frame from the Sunglasses Rx collection and choose the matching Rx type in the lens step. If you're building in an ADD, favor frames that aren't too shallow from top to bottom, since the reading area sits in the lower part of the lens.
Before you orderThe Squint Clue: Why Dark Lenses Expose an Old Rx
Here's something tint guides rarely mention. Your eye works a lot like a camera, and the pupil is its aperture. In bright light it narrows, often to somewhere around 2 to 4 millimeters. In dim light it can open well past 6.
A narrow aperture is forgiving. It increases depth of focus, the range over which things look acceptably sharp, so a small focusing error can slip by unnoticed on a bright day. It's also why squinting works: narrowing your eyelids turns your eye into a rough pinhole camera.
Now put on dark lenses. Less light reaches the eye, the pupil opens wider and depth of focus shrinks. The forgiveness goes away. Numbers that are slightly out of date, or a small astigmatism you decided to skip, can show up in your Sunglasses Rx even though your clear glasses seemed fine outdoors.
That gives you a free check before you spend anything:
- On a bright day, wear your clear glasses and find a sign you can only just read: a street name, a license plate across the parking lot.
- Squint slightly and look again.
- If squinting makes it clearly sharper, your eyes are leaning on the pinhole trick to make up for your lenses. Dark lenses will take that trick away, so book an exam before you order.
- If squinting changes nothing, your distance numbers are probably doing their job.
This isn't an eye exam. It only tells you whether to get one first.
The same physics touches reading. With an ADD, close-up focus already depends on a limited sharp zone. A wider pupil narrows the range of distances that look crisp, which is one reason a patio menu can feel harder to read through dark sunglasses than through clear readers. If you read outdoors often, a medium tint can be easier to live with than the darkest option.
PaperworkGetting Your Numbers: U.S. Rules Work in Your Favor
You don't need anyone's permission to order Sunglasses Rx from wherever you like. A few rules and habits make it straightforward.
- You're owed a copy. Under the FTC's Eyeglass Rule, your eye doctor has to give you a copy of your eyeglass prescription after an exam, whether or not you ask, and can't make you buy glasses there to get it. Since 2024, offices also have to ask you to confirm you received it.
- Prescriptions expire. Most states set a window of one or two years. Retailers generally ask for a current one, and the Squint Clue is a good reason to respect that window rather than stretch it.
- Pupillary distance isn't always printed. The distance between your pupils is what centers each lens in front of each eye. The Eyeglass Rule doesn't require it on the slip, so ask for it at the exam or measure it at home.
- Keep both pairs on the same numbers. If your Rx changed since you bought your clear glasses, mixing an old clear pair with a new sun pair means your eyes switch between two settings every time you step outside.
When the box arrivesThe Reference Pair Check: Your First Day With Sunglasses Rx
You already own the best testing tool there is: your clear glasses. If both pairs were made from the same numbers, they should agree. Where they disagree tells you where to look. (If your sun pair is distance-only and your clear pair has an ADD, compare distance only.)
-
The sign swap
Stand in one spot, look at the same distant sign and switch pairs.
Softer only in bright sun? Revisit the Squint Clue. Softer even in shade? The order details are the likelier cause, so contact support with the numbers from both pairs.
-
The one-eye swap
Cover one eye, then the other, with each pair on.
This shows whether the problem lives in one lens or both, which speeds up any remake.
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The seat check
In a mirror, note where your pupils sit within each lens: centered, higher, lower, closer to the nose.
A sun pair that sits noticeably lower or wider puts you behind a different part of the lens. It matters most with an ADD. Nose pad adjustment or a better-fitting frame fixes this; new numbers don't.
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The curb test
Walk down a few steps or off a curb.
A new frame can make the ground seem to tilt for a moment. If the numbers match a pair you already wear comfortably, that should fade within a day or two.
Why matching numbers shouldn't need a long break-in
Adjustment periods mostly come from change: new numbers, or a lens design you've never worn, like a first progressive. If your Sunglasses Rx copies numbers and a lens type you already wear every day, a long adjustment is a signal, not a phase. Don't wait it out for weeks. Run the checks above and reach out.
FAQSunglasses Rx Questions, Answered Briefly
Do prescription sunglasses use the same prescription as glasses?
Usually, yes, for distance. The exceptions are deciding whether to include your ADD, not copying a computer-specific pair, and not using a contact lens prescription.
Can I use my contact lens prescription for Sunglasses Rx?
No. Glasses sit farther from the eye than contacts, which changes the power needed at higher prescriptions, and contact prescriptions include measurements that don't apply to glasses. Use your glasses prescription.
Can I get Sunglasses Rx with progressive lenses?
Yes. A progressive or lined bifocal sun lens lets you read outdoors without switching pairs. If you rarely read while it's sunny, distance-only lenses give a wider sharp view and often cost less.
How long does it take to get used to Sunglasses Rx?
If the numbers and lens type match glasses you already wear, usually a day or two at most. A new prescription or a first progressive lens can take longer. If discomfort lasts beyond that, check the fit and the numbers rather than waiting.
Do I need a new eye exam before ordering?
If your prescription has expired, or if squinting through your clear glasses makes distant signs noticeably sharper, yes. Otherwise, a current prescription is all you need.
Numbers First, Then the Fun Part
Settle which version of your Rx belongs in the sun pair, make sure it's current, and the frame and tint choices get a lot simpler. When you know your row in the Sun Script, browse Sunglasses Rx and try frames on with your camera before you choose.
About this guide. Written by the Aoolia Editorial Team. The optics described here, including pupil size, depth of focus and the distance between a lens and the eye, are standard textbook principles. U.S. rules referenced are the FTC Eyeglass Rule (16 CFR Part 456) and FDA guidance for contact lens wearers. We update this page when those rules or our lens options change.
This guide is general information, not a substitute for an eye exam. If your eyes feel unusually sensitive to light or your vision changes, see your eye doctor.
