Contact Lens Supply Duration Calculator
See how long your boxes of daily disposable contact lenses will last based on how many days a week you wear them.
How it works
Total lenses = boxes × lenses per box · Weeks = total ÷ (days per week × eyes)
Daily disposable contact lenses are single-use: one fresh lens per eye per wearing day. Your stock therefore lasts as long as your total lens count divided by how many you go through each week, which depends on both the number of eyes wearing lenses and how many days a week you actually wear them. Part-time wearers who switch to glasses on some days stretch a supply well beyond the box count suggests.
Worked example
Four 30-lens boxes hold 120 lenses. Wearing both eyes all 7 days uses 14 lenses a week, so the supply lasts 120 ÷ 14 ≈ 8.6 weeks, or about 60 calendar days.
Frequently asked questions
Does this work for monthly or two-week lenses?
This is built for daily disposables, where you use a new lens each day. For monthly or bi-weekly lenses, one lens serves many days, so the duration is driven by the replacement schedule instead of the lens count.
Should I reuse daily lenses to save money?
No. Daily disposables are not designed to be cleaned and reworn; reusing them raises the risk of eye infections. Choose a reusable lens type if you want per-lens longevity.
How much buffer should I keep?
Ordering a little early is wise, since a lens can tear or a box can be defective. Many wearers reorder when they have about two weeks left.
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Educational estimate only, not medical advice — talk to an eye doctor, dentist, dermatologist or other qualified professional about your own care.