Eye Drop Supply Duration Calculator
Calculate how many days your eye drop bottle will last based on drops per day, eyes treated, and bottle size.
Never run out unexpectedly.
Eye drops are expensive, and running out mid-prescription can be a real problem — especially for glaucoma patients or people using steroid drops after surgery. This calculator tells you exactly how many days a bottle will last.
The formula:
Total Drops = Bottle Volume (mL) × Drops per mL
Days Supply = Total Drops ÷ (Drops per Dose × Doses per Day × Eyes Treated)
Standard drop size: A single eye drop is approximately 0.05 mL (50 microliters). This means 1 mL of solution = about 20 drops.
| Bottle Size | Approximate Total Drops |
|---|---|
| 2.5 mL | ~50 drops |
| 5 mL | ~100 drops |
| 7.5 mL | ~150 drops |
| 10 mL | ~200 drops |
| 15 mL | ~300 drops |
Common dosing schedules:
| Medication Type | Typical Frequency |
|---|---|
| Glaucoma drops | Once or twice daily |
| Antibiotic eye drops | 4–6 times per day |
| Steroid eye drops | 4 times per day (tapering) |
| Artificial tears | 2–4 times per day as needed |
| Allergy eye drops | Once or twice daily |
Practical tips:
- Press on the inner corner of your eye for 1–2 minutes after instillation. This reduces drainage and increases how much medication is absorbed.
- Wait 5 minutes between different eye drops if using multiple medications.
- Eye drops typically expire 28 days after opening, regardless of how much is left.
- Store drops as directed — some require refrigeration.
- If you miss a dose, apply it as soon as you remember (unless it is almost time for the next dose).
- Always wash your hands before applying eye drops.
Insurance and refill timing: Most pharmacies will not refill a prescription early. Use this calculator to predict your refill date and request it 2–3 days before running out.