Free tool
Contact lens annual supply calculator
How many boxes of daily disposables does a year actually take? Enter the days a week you wear lenses, the packs already in the house, and the count printed on the carton, and this works out the order per eye, the packs that spill past the period, and the date the supply runs out. Everything runs in your browser.
Last reviewed 2026-08-14. Prescription and ordering rules come from 16 CFR Part 315, the FTC Contact Lens Rule.
Your wear pattern
Daily disposables are counted per eye, one sealed pack per eye per wearing day. Everything is calculated in your browser and nothing is uploaded.
Adding a date counts real calendar days, including any leap day, and returns the date your supply runs out.
Count the days you actually put lenses in. Glasses days, sick days, and travel days you skip all belong outside this number.
Read the count off the carton. It counts individual lenses for one eye, not pairs, which is why a box of 90 is roughly three months of one eye rather than three months of wearing lenses.
A buffer for torn lenses, dropped lenses, and the occasional pack that never settles comfortably.
Use the delivered price for the box size selected above, after shipping and any offer you have confirmed.
Your supply plan
Boxes to buy
10
90 lenses per box, 900 packs in total
Wearing days covered
365
across 365 calendar days (12 months)
| Per eye | Right eye (OD) | Left eye (OS) |
|---|---|---|
| Wearing days in the period | 365 | 365 |
| Packs on hand | 0 | 0 |
| Packs still needed, spares included | 370 | 370 |
| Boxes of 90 to order | 5 | 5 |
| Packs left over at the end | 80 | 80 |
| Supply runs out | after 450 days | after 450 days |
| Box size | Right | Left | Total boxes | Packs over |
|---|---|---|---|---|
| 30 | 13 | 13 | 26 | 40 |
| 90 | 5 | 5 | 10 | 160 |
| 180 | 3 | 3 | 6 | 340 |
Not every product is made in every count, and a larger box is not automatically cheaper per lens. Check which counts your prescribed lens is sold in before planning around one.
Before you order
160 packs land beyond what this period needs
Boxes are sold whole, so the last box of each eye overshoots. Those packs roll into the next period and are worth roughly 80 more days of paired wear, provided the foil dates still reach that far.
900 sealed packs have to live somewhere
A supply this size arrives as identical looking boxes with small print on one edge. A hard-shell Sturdysight organizer keeps the packs you are working through upright, labeled left and right, and countable at a glance, so you can see what is left without emptying a drawer. It is a dry organizer for unopened daily-disposable packs only, never a soaking case, and it never holds a bare lens or solution.
Shop Medium on AmazonNot sure which size? Use the case size finder.
This is an inventory planning estimate built from the numbers you entered. It does not set a wearing schedule, does not extend a replacement interval, and is not medical advice. Follow your prescription, the product labeling, and your eye care provider.
A box of 90 is 90 lenses for one eye, and almost every mistake starts there
Daily disposable contact lenses are packaged and priced by the individual lens. A carton labeled 90 holds 90 sealed blister packs, each holding one lens, and every one of them goes in the same eye. It is not 45 pairs. It is not ninety days of wearing lenses. It is ninety days of one eye, which means a two-eye wearer gets forty-five days out of it and then buys another one.
That single detail decides the whole order. It is also why the phrase annual supply causes so much trouble: it is a purchasing term, not a measurement of your year. Eight boxes of 90 is a common way to sell an annual supply, and the arithmetic behind it is four boxes per eye, 360 lenses per eye, 360 wearing days. Five days short of a calendar year, and only if you wear lenses every single day. If you wear them five days a week, those same eight boxes cover roughly sixteen months and you are buying a fifth of a year you did not use.
Here is what a year costs in lenses at each wear pattern, per eye, before any spare buffer. Wearing days are 365 multiplied by the days per week and divided by 7. Box counts are those days divided by the box size and rounded up, once per eye, then doubled for both eyes.
| Wear pattern | Lenses per eye per year | Boxes of 30, both eyes | Boxes of 90, both eyes | Boxes of 180, both eyes |
|---|---|---|---|---|
| 7 days a week | 365 | 26 | 10 | 6 |
| 6 days a week | 313 | 22 | 8 | 4 |
| 5 days a week | 261 | 18 | 6 | 4 |
| 4 days a week | 209 | 14 | 6 | 4 |
| 3 days a week | 156 | 12 | 4 | 2 |
| 2 days a week | 104 | 8 | 4 | 2 |
Two things fall out of the table immediately. Rounding up to whole boxes matters more at large box sizes: at four days a week, boxes of 180 deliver 720 lenses against a need of 418, so more than 300 packs carry into the following year. And moving from four days a week to five adds no boxes at all in the 90 and 180 columns, because the rounding already covered it, while the 30 column climbs by four. Not every product is sold in every count, so check which counts your prescribed lens comes in before planning around one.
Two clocks decide how far ahead you can buy
Stocking up is usually the cheapest way to buy lenses, and there is a point past which it stops being a good idea. Two independent dates set that point, and they have nothing to do with each other.
The prescription clock
A contact lens prescription expires. Under 16 CFR 315.6, the expiration date is whatever a state law specifies if that date is one year or more after the issue date, and otherwise not less than one year after the issue date. A prescriber can set a shorter date, but only on the basis of medical judgment about the ocular health of the patient, and that reason has to be documented in your record, kept for at least three years, and made available to the FTC on request. A one-year minimum with a documented exception is the floor, not a suggestion.
Two practical consequences follow. First, a seller filling your order either takes the prescription directly or verifies it with your prescriber, and the verification request carries the quantity you ordered along with the lens parameters. A prescription that states a quantity is part of what gets checked. Second, the timing that matters is the date the order is placed. A prescription with four months left is a valid basis for an order today, and it is not a valid basis for an order in five months.
If you do not have a copy of your prescription, that is worth a phone call before you start shopping rather than at the moment an order is held. At the end of a contact lens fitting, the prescriber has to give you the prescription whether or not you ask for it, may not charge an additional fee for it, and may not require you to buy lenses in exchange for it. On the verification route, if a prescriber does not respond within eight business hours of a complete request, the order can be filled.
The foil clock
Every sealed blister pack carries a date printed on the foil, and that date belongs to the pack rather than to the carton it arrived in. A deep supply is a supply where some packs sit for a long time, and the ones at the back of the drawer are the ones nobody checks. This is the real argument against buying two years deep on a product you may stop wearing after your next examination.
The fix is rotation rather than restraint. Work through the oldest dates first, keep the packs you are currently using where you can see them, and check the foil rather than the box whenever stock has been sitting. The pack expiration tracker sorts a pile of packs into that order and flags the ones you would not reach in time.
Six ways the box count goes wrong
These are the errors that survive year after year, because a reorder that is slightly wrong still produces lenses in a box and nothing announces the mistake.
Counting pairs instead of lenses
A box of 90 daily disposables holds 90 individual lenses for one eye. It is not 45 pairs, and it is not three months of wearing lenses. It is three months of one eye. Half the confusion about annual supply totals starts and ends here.
Buying for seven days a week when you wear five
A five day a week wearer needs 261 lenses per eye across a year rather than 365. That is two fewer boxes of 90 per eye than a full-time wearer, or four boxes across both eyes, bought every single year until somebody notices.
Ordering in matched pairs when the eyes differ
Monovision wearers, people corrected in one eye only, and anyone whose second eye tolerates a longer stretch between lenses do not consume both eyes at the same rate. Boxes are sold per eye for exactly this reason.
Ignoring what is already in the drawer
Most reorders happen with unopened packs still in the house. Counting them first is the difference between an annual supply and an annual supply plus whatever you forgot you had.
Planning zero spares
The opposite error. A torn lens, a dropped lens, or a lens that will not settle costs a pack with nothing behind it, and an emergency single box bought at retail speed rarely carries the price you planned around.
Treating the last box as fully used
Boxes are sold whole. If you need 261 lenses and the box holds 90, you buy 270 and carry 9 forward. Those carried packs are real inventory, and they are the ones most likely to reach the date printed on the foil unnoticed.
Quantity is one decision. Timing is a different one.
Once you know the number of boxes, three separate calendars want a say in when you press the button, and none of them is the same as the prescription date.
Manufacturer rebate programs commonly set a minimum box count, which is why the difference between three and four boxes per eye sometimes changes the delivered price more than the price per box does. Terms and minimums change, and they change per product, so confirm the current offer before letting it decide the quantity. Our rebates and promo codes guide covers what to check.
Vision benefits usually work on an allowance that resets, and a flexible spending account works on a deadline that does not forgive. If you are buying with either, the quantity you calculate here and the money available are two halves of the same order. The FSA and HSA planner works out the spending deadline and how much supply the remaining balance covers, and the vision insurance guide covers how contact lens allowances are usually structured.
Then there is the plain question of where the same quantity costs least once shipping and offers are settled. That is a per-order comparison rather than a permanent answer, which is what the cost calculator and the reorder comparison are for.
Ten boxes arrive on a Tuesday. Then the storage question starts.
A year of daily disposables for two eyes is somewhere between 500 and 900 sealed packs depending on your schedule and the rounding. That quantity does not fit the mental model most people have of buying contacts, which is a small box in a bathroom cabinet. It arrives as a stack of identical cartons with the parameters printed small on one edge, and the eye it belongs to is one line of that small print.
There are two jobs to solve, and they are different. The deep supply, the boxes you will not touch for months, wants to stay in its original packaging somewhere cool, dry, and dark, with the oldest dates in front. The working supply, the packs you are actually reaching for each morning, wants to be visible, separated by eye, and countable without picking anything up. Mixing those two jobs into one drawer is how people end up with an unknown quantity of an unknown eye and a reorder placed on a guess.
That working supply is the job a Sturdysight organizer does. It is a hard-shell organizer for sealed, unopened daily-disposable blister packs, sold in Small, Medium, and Large as a paired set of two eye-specific cases, one labeled L and one labeled R. Packs stand upright and stay separated by eye, so the count is a glance rather than an audit. It is a dry organizer for unopened packs only. It is never a soaking case, and it never holds a bare lens or solution, both of which belong in the case and solution your prescribed care system specifies.
Sizing follows from the staging decision rather than from the annual total. Deciding to keep a month at hand and the rest in the cupboard points somewhere different from keeping a full quarter out. Compare your own unopened packs against the current product photos, since pack shape varies by brand and by package generation, and the case size finder walks through that in four questions. The organizer guide covers the storage setup in more detail.
Frequently asked questions
How many boxes of contacts do I need for a year?
For daily disposables worn seven days a week, one eye consumes 365 lenses a year, so both eyes consume 730. In boxes of 90 that is 5 boxes per eye and 10 boxes in total, which delivers 900 lenses and leaves 170 over. In boxes of 30 it is 13 per eye and 26 in total. If you wear lenses five days a week the figure drops to 261 lenses per eye, or 3 boxes of 90 per eye. Reusable lenses work differently, because each lens covers the whole replacement interval on your prescription rather than one day.
Why is an annual supply of daily disposables often sold as 8 boxes of 90?
Eight boxes of 90 is 720 lenses, which is 4 boxes and 360 lenses per eye. At seven day wear that covers 360 wearing days, five days short of a calendar year, and it assumes you wear lenses every day. It is a purchasing convention that rounds to whole boxes rather than a measurement of your year. If you wear lenses fewer than seven days a week, the same eight boxes stretch well past twelve months.
Does a box of 90 contact lenses mean 90 days of wear?
Ninety days for one eye. Wearing lenses in both eyes consumes two packs a day, so two boxes of 90 cover 90 days of two-eye wear. The count on the carton is always individual lenses, which is why a paired quantity has to be worked out per eye.
Can I buy more than a year of contact lenses at once?
Orders are placed against an unexpired prescription, and prescriptions carry an expiration date that is at least one year from the issue date under the FTC Contact Lens Rule unless the prescriber documents a medical reason for a shorter term. A prescription may also state a quantity, and a seller verifying an order sends the quantity ordered to the prescriber. Beyond the paperwork there is the practical limit: every pack carries a date printed on the foil, and a supply bought two years deep is a supply where the back of the drawer is racing that date.
How many spare packs should I plan?
There is no official figure, which is why this calculator asks rather than assumes. The buffer exists for torn lenses, dropped lenses, and packs that never settle comfortably. Setting it to zero means any loss comes straight out of a wearing day, and setting it high mostly costs you drawer space and a slightly earlier reorder.
Do I have to buy my lenses from the prescriber who fitted me?
No. Under the FTC Contact Lens Rule the prescriber must give you a copy of your contact lens prescription at the end of the fitting whether or not you ask for it, at no extra charge, and may not require you to buy lenses in exchange for it. You can take that prescription to any seller. This calculator works out the quantity; where you buy it is a separate decision.
Does this calculator work for monthly or two-week lenses?
It is built for daily disposables, where one sealed pack equals one wearing day per eye. Reusable lenses consume one lens per replacement interval instead, so a different calculation applies. Use the replacement reminder calculator for those, and enter the exact interval from your prescription rather than a label such as monthly.
Is anything I enter here stored or sent anywhere?
No. The whole calculation runs in your browser tab. Nothing about your prescription, your schedule, or your inventory is uploaded, saved to an account, or transmitted, and closing the tab discards it.
Sources
Prescription release, expiration, and verification rules on this page come from the current text of the FTC Contact Lens Rule and federal consumer health guidance. Box counts, product availability, rebate terms, and benefit rules come from the manufacturer, the seller, or your plan, and all of them change. Check the current text before relying on any of it, and treat your own prescription and your eye care provider as the authority on your eyes.
- 16 CFR Part 315, the FTC Contact Lens Rule
- 16 CFR 315.6, expiration date of a contact lens prescription, including the one-year minimum
- FTC, The Contact Lens Rule: A Guide for Prescribers and Sellers, covering automatic release and the eight business hour verification window
- FTC consumer guidance, Buying Prescription Glasses or Contact Lenses: Your Rights
- FDA, Types of Contact Lenses, on daily disposable wear and manufacturer replacement schedules
- FDA, Buying Contact Lenses
- CDC, About Contact Lenses, on wearing, cleaning, and storing lenses as directed