Prescription Refill Calculator
Free medication refill date calculator with advanced tracking for tablets, liquids, and controlled substances.
Advanced Refill Calculator
Calculate refill dates, days supply, and manage multiple medications
Medication Adherence Tips
- • Set phone reminders 3-5 days before refill date
- • Enable automatic refills at your pharmacy
- • Keep this calculator bookmarked for easy access
Essential Prescription Guides
Expert articles to help you manage your medications effectively
How to Calculate Your Prescription Refill Date
Learn the exact formula pharmacies use to determine when you can refill your medications. Understand the 28-day rule, 30-day supplies, and early refill policies at major pharmacies.
Read Complete GuideControlled Substance Refill Rules Explained
Everything you need to know about Schedule II-V controlled substances, refill restrictions, early refill limitations, and how to stay compliant with federal and state regulations.
Learn MoreDays Supply Calculator for All Medication Forms
Master the days supply calculation formula for tablets, liquids, inhalers, and injections. Includes real-world examples and pharmacy technician tips for accurate calculations.
Calculate NowMedication Adherence: Best Practices
Discover proven strategies to never miss a dose. Set up automatic refills, use pill organizers, sync multiple medications, and leverage pharmacy apps for better health outcomes.
Track MedicationsComplete Guide to Prescription Refill Management
Everything you need to know about calculating refill dates, days supply, and managing your medications effectively
Understanding Prescription Refills
Prescription refill management is crucial for maintaining consistent health outcomes. Understanding days supply calculations, pharmacy policies, and controlled substance regulations ensures you never miss a dose. This calculator helps you navigate these complex factors with precision and ease, supporting 28-day, 30-day, and 90-day prescription cycles.
- Days Supply: Total days medication lasts
- Fill Date: When prescription was dispensed
- Refill Date: Earliest next refill allowed
- Early Refill: Pharmacy-specific grace period
Controlled Substance Compliance
Controlled substances (Schedule II-V medications like pain relievers, ADHD treatments, anxiety medications) are strictly regulated by federal and state laws. Refills are typically allowed only after 75-80% of the medication has been used. For a 30-day supply, this means you can refill approximately 2 days early. Our calculator automatically accounts for these regulations.
- Schedule II: No refills, new Rx required
- Schedule III-IV: Up to 5 refills in 6 months
- Schedule V: Standard refill rules apply
- Early Refill: Usually 2 days for all schedules
Medication Adherence Strategies
Taking your medication as prescribed is vital for treatment effectiveness. Studies show that proper medication adherence improves health outcomes by 40-60%. Use our multi-medication tracker to synchronize refill dates, reducing pharmacy visits and simplifying complex regimens. Combine this tool with pill organizers, phone reminders, and automatic refill services for optimal results.
- Use daily pill organizers for visual tracking
- Set multiple phone reminders throughout day
- Link medication times to daily routines
- Track adherence with mobile apps
Insurance & Cost Optimization
Insurance plans often limit early refills to control costs and prevent medication stockpiling. Understanding your specific plan's policies can help you avoid unexpected denials. Most insurance companies follow the 75-80% rule for refills. If a refill is denied, contact your insurance provider and doctor promptly, especially if prior authorization is required for certain medications.
- Switch to 90-day supplies for lower copays
- Use mail-order pharmacy for maintenance drugs
- Ask about generic alternatives
- Check manufacturer savings programs
How to Calculate Prescription Refills
30-Day Prescriptions
Formula: Fill Date + 29 days = Last dose
Next Refill: Last dose + 1 day
Early Refill: Usually 2-3 days before
90-Day Prescriptions
Formula: Fill Date + 89 days = Last dose
Next Refill: Last dose + 1 day
Early Refill: Usually 7-10 days before
Days Supply Calculation
Formula: Total Quantity ÷ (Dose × Frequency)
Example: 60 tablets ÷ (1 × 2/day) = 30 days
Liquids: Total mL ÷ (Dose mL × Frequency)
Frequently Asked Questions
Common questions about prescription refills, days supply, and medication management
How do you calculate prescription refill date?
To calculate a 30-day prescription refill: (1) Write down your first dose date, (2) Add 29 days to that date, (3) The result is your last dose date, (4) Your next refill period begins the day after (+30 days total). For 28-day prescriptions, add 27 days. For 90-day prescriptions, add 89 days. Our calculator automates this process and accounts for early refill policies based on your selected pharmacy.
What is the 28 day prescription refill rule?
The 28-day prescription rule (sometimes called the "28-day refill rule" or "80% rule") requires at least 28 days between refills of 30-day prescriptions, especially for controlled substances. This means you've used approximately 80% of your medication before getting a refill. In practice, most pharmacies allow refills 2 days early for 30-day supplies (after 28 days). Insurance companies enforce this to prevent medication stockpiling and early refills.
How early can I refill my prescription at CVS or Walgreens?
CVS Pharmacy: Regular medications can be refilled 3-5 days early, controlled substances 2 days early. Walgreens: Standard medications 3 days early, controlled substances 2 days early. Walmart: 4-day early refill for regular medications with strict controlled substance monitoring. Rite Aid: 3-day early refill with enhanced adherence programs available. Always verify specific policies with your local pharmacy as some states may have stricter regulations.
How do you calculate days supply for liquid medications?
Formula: Days Supply = Total Volume (mL) ÷ (Dose Volume × Daily Frequency)
Example 1: 120mL bottle, 5mL dose, twice daily = 120 ÷ (5 × 2) = 120 ÷ 10 = 12 days supply
Example 2: 240mL bottle, 10mL dose, three times daily = 240 ÷ (10 × 3) = 240 ÷ 30 = 8 days supply
Use our "Days Supply" calculator tab above for instant calculations with step-by-step results.
Can controlled substances be refilled early?
Controlled substances have much stricter refill rules than regular medications. Most pharmacies allow refills only after 75-80% of the medication has been used—typically 2 days early for a 30-day supply. Schedule II controlled substances (like Adderall, OxyContin, Ritalin) cannot be refilled early without a new prescription from your doctor. Schedule III-V controlled substances may allow limited early refills but are closely monitored by state prescription drug monitoring programs (PDMP).