Prescription Refill Date Calculator
Calculate your next refill date, earliest insurance-allowed refill, and track multiple prescriptions at a glance. Never miss a refill again.
Calculate Refill Date
Disclaimer: This calculator provides estimated dates only. Actual refill eligibility depends on your insurance plan, state regulations, and pharmacy policies. Always confirm with your pharmacy.
About This Tool
What Is a Prescription Refill Calculator?
A prescription refill calculator helps you determine when your current medication supply will run out and when you're eligible to refill under your insurance plan. By entering your last fill date and day supply, you get an exact refill date along with the earliest date your insurance will typically cover a refill.
How to Calculate Your Refill Date
The formula is simple: Refill Date = Last Fill Date + Day Supply. For a 30-day supply filled on January 1, your refill date is January 31. The earliest insurance refill is calculated as: Earliest Refill = Last Fill Date + (Day Supply × Early Fill %). At 75%, that would be January 1 + 22.5 days = approximately January 23.
Understanding Day Supply
Day supply represents how many days your dispensed medication should last when taken as directed. Common day supplies include:
- 30 days — Standard retail pharmacy fill, the most common for monthly prescriptions.
- 60 days — Some plans allow this for maintenance medications.
- 90 days — Mail-order pharmacies typically dispense 90-day supplies, often at a lower per-day cost.
Early Refill Policies
Insurance companies use early refill thresholds to prevent stockpiling and fraud while ensuring patients don't run out of medication. The most common threshold is 75%, meaning you can refill after using 75% of your current supply. For a 30-day prescription, that's around day 22–23.
Important exceptions include:
- Controlled substances: Schedule II medications (opioids, stimulants like Adderall) typically cannot be refilled early and may require a new prescription each time.
- Lost or stolen medications: Many pharmacies will fill an early refill for a lost/stolen claim once, but your insurance may not cover it.
- Dose changes: If your doctor changes your dose, the pharmacy can usually override the early refill restriction.
💡 Pro Tips
- Set a phone reminder 3–5 days before your refill date so you never run out.
- Switch to 90-day mail-order for maintenance medications — most plans charge 2 copays for 3 months of medication.
- Sync all your prescriptions to the same refill date by asking your pharmacy about "med sync" programs.
- Keep a record of your fill dates — this calculator's multi-medication tracker can help.
- If traveling internationally, carry medications in original bottles with labels, plus a letter from your doctor for controlled substances.
Key References
- U.S. Food & Drug Administration. Buying & Using Medicine Safely. FDA.gov, 2024.
- Centers for Medicare & Medicaid Services. Prescription Drug Coverage — General Information. CMS.gov, 2024.
- Drug Enforcement Administration. Practitioner's Manual — Controlled Substance Refills. 21 CFR 1306, 2024.
Formula last verified: February 2026