How long does a box of contacts last?
A box of contacts lasts as long as the lens count divided by how many lenses you go through per replacement. A 90-pack of daily lenses covers one eye for 90 days, or both eyes for 45 days if both eyes share the same prescription.
Most people buy by the box and run out by surprise. The math takes one minute.
How do you do the math?
Three numbers:
- Lenses in the box. It is printed on the box: 30, 90, 6, and so on.
- Replacement schedule. Daily lenses are one wear, then thrown away. Two-week and monthly lenses are replaced on the schedule your eye doctor prescribed.
- Eyes on that box. If your two eyes have different prescriptions, each eye needs its own boxes. If they match, one box can serve both eyes, and it runs out twice as fast.
Days a box lasts = lenses in the box × days per lens ÷ eyes using that box.
For dailies, "days per lens" is one wear day. The FDA defines a true daily disposable schedule as a brand new pair of lenses each day.
How long do common box sizes last?
Assuming you wear lenses every day and replace on schedule:
| Box | One eye | Both eyes, same prescription |
|---|---|---|
| 30-pack of dailies | 30 days | 15 days |
| 90-pack of dailies | 90 days | 45 days |
| 6-pack of two-week lenses | 12 weeks | 6 weeks |
| 6-pack of monthly lenses | 6 months | 3 months |
If your eyes have different prescriptions, use the "one eye" column for each eye's boxes.
How many boxes is a year's supply?
For daily lenses worn every day, a full year for both eyes is 365 × 2 = 730 lenses.
Manufacturers usually round that to 720. ACUVUE counts an annual supply of its 1-day lenses as 720 lenses, and CooperVision's current rebate for MyDay dailies asks for eight 90-packs. Eight 90-packs is 720 lenses: 360 days per eye, about 5 days short of a calendar year. Twenty-four 30-packs is also 720.
For reusable lenses, the manufacturer counts are smaller. CooperVision's current rebate for Biofinity monthlies asks for four 6-packs, 24 lenses, which is 12 months for each eye. ACUVUE counts 48 lenses as an annual supply of its two-week lens.
Buying the year at once is often tied to a rebate. How those work is in how do contact lens rebates work.
What if you don't wear contacts every day?
Dailies stretch in calendar time because you only open a pair on the days you wear them. Wear them three days a week and a 90-pack for one eye lasts about 30 weeks.
Reusable lenses are different. Two-week and monthly lenses are replaced on a schedule, and skipping days does not automatically buy you more time. Ask your eye doctor how to count part-time wear on your lens. Do not guess.
For how long you can wear dailies in a single day, see how long can you wear daily contacts.
Can you make a box last longer?
Not safely. Reusing a daily lens, or wearing a two-week or monthly lens past its schedule, does not save a box. It stretches a medical device past what it was made for. The FDA tells wearers to follow their eye doctor's directions, and the CDC says to follow the replacement schedule your eye care provider recommends.
What actually helps:
- Count before you run out. When you open a box, note the date it should run out.
- Keep backup glasses. The CDC recommends carrying backup glasses with a current prescription for days you need to take lenses out.
- Order before the last week. Shipping and prescription verification both take time.
Should you buy more than your prescription covers?
No. Under the federal Contact Lens Rule, a contact lens prescription generally lasts at least one year, unless your eye doctor sets a shorter date for a medical reason. If your prescription changes, the leftover boxes in the old power may not be right for your eyes. Buy for the prescription you have. If it has lapsed, see expired contact prescriptions.
Also check the expiration date printed on each box before you open a blister.
FAQ
How long does a 90-pack of daily contacts last?
90 days for one eye. If both eyes use the same prescription and share the box, 45 days. That assumes a fresh lens in each eye every day you wear them.
How many boxes of daily contacts do you need for a year?
For every-day wear in both eyes, about 730 lenses. Manufacturers usually call 720 lenses an annual supply, which is eight 90-packs or twenty-four 30-packs. That covers 360 days per eye.
How long does a 6-pack of monthly contacts last?
Six months for one eye, or three months if both eyes share the same prescription and the same box. Replace on the schedule your eye doctor gave you.
Sources
- FDA: Types of Contact Lenses (disposable and replacement schedules)
- FDA: Contact Lens Care
- CDC: Preventing Eye Infections When Wearing Contacts
- Johnson & Johnson Vision: ACUVUE rewards annual supply chart (PDF)
- CooperVision: 2026 current wearer rebate, annual supply quantities (PDF)
- eCFR: 16 CFR Part 315, Contact Lens Rule (prescription expiration, 315.6)
tuesday is prescription daily contacts on a monthly subscription, launching soon. Each box will be a month of lenses for both eyes, so the math is done for you. At launch, we'll verify your prescription with your prescriber before anything ships. Join the waitlist.