Contact Lens Schedule Calculator
Next lens change date and supply count from start date and wear schedule.
What it does
Contact lens schedules count from the day a pair is opened, not from days actually worn. A monthly pair opened on the 10th retires 30 days later even if it sat out half those mornings.
The tool above takes the opening date with lens type, eyes, and days to cover. It returns the next change date with the lens and pair counts.
The default Mar 10 2026 start on 2-week lenses for both eyes gives Tue Mar 24 2026 with 14 lenses for 90 days. A daily one-eye month needs 30 lenses by the same math.
Intervals follow FDA lens guidance with American Optometric Association replacement wording behind it. Both cap wear at the schedule and put fresh solution above every shortcut.
How to use
- Enter the opening date.
- Pick the replacement type.
- Pick one or both eyes.
- Enter days of supply to cover.
- Read the next change date first.
- Buy the lens count beside it.
Formula
- start
- Day the lenses are opened, counting starts here.
- interval
- Wear interval: 1, 14, 30, or 90 days.
- cover
- Days of supply to count out.
- eyes
- 2 for both eyes, 1 for one eye.
Day counts run whole days in UTC, so month length and leap days land correctly. Quarterly counts 90 days. Intervals cap at package opening, and worn hours never extend them.
Worked example
Example: 2-week lenses from March 10
Defaults: opened Mar 10 2026, 2-week lenses, both eyes, 90 days.
- Start Mar 10 2026, 2-week lenses, both eyes, 90 days cover.
- Next change: Mar 10 + 14 days = Tue Mar 24 2026.
- Changes per eye: 90 / 14 = 6.43, round up to 7.
- Lenses: 7 x 2 eyes = 14 lenses, 7 pairs.
- Count starts at opening, not at days worn.
- Tool shows Tue Mar 24 2026, 14 lenses (7 pairs), 7 changes per eye.
Reference table
| Type | Days | Count rule |
|---|---|---|
| Daily disposable | 1 | New pair each day |
| 2-week | 14 | Discard 14 days after opening |
| Monthly | 30 | Discard 30 days after opening |
| Quarterly | 90 | Discard 90 days after opening |
Limits
- Estimates for information only, not eye care advice.
- Prescriptions and fits need the eye doctor.
- Infection signs override every schedule here.
- Sleeping in lenses needs specific approval.
Common mistakes
- Counting only days worn.
- Topping off old solution.
- Rinsing with tap water.
- Keeping the case past 6 months.
- Stretching monthlies into month two.
Try it yourself
Quick checks. Answers sit tucked under each question.
Daily, one eye, 30 days from Mar 10?
Next day Mar 11 2026, 30 changes, 30 lenses (15 pairs).
Monthly, both eyes, 90 days from Jan 15?
Next Feb 14 2026, 3 changes per eye, 6 lenses (3 pairs).
2-week, one eye, 28 days from Mar 10?
Next Mar 24 2026, 2 changes per eye, 2 lenses (1 pair).
Questions
Do part time wearers stretch intervals?
Yes for counting: even part time pairs expire at the interval end. Open the next pair on schedule.
Is monthly a calendar month?
No. Monthly means 30 days here; calendar month counting lands within a day or two either way.
How often is the lens case replaced?
Replace the case every 3 to 6 months, rinse with fresh solution, air dry face down.
Can tap water rinse lenses?
No. Tap water carries infection risk. Use fresh solution only, never top off old liquid.
What if a lens tears mid cycle?
Discard it and open a fresh pair. Red eyes or pain need the eye doctor, not waiting.
How long is extended wear?
Up to 30 days continuous for approved extended wear, then discard and rest eyes overnight.