Prescription Refill
Calculate your next prescription refill date and days supply for tablets or liquid medications. Free online medication refill planner for patients and caregivers.
About This Calculator
The Prescription Refill Calculator helps patients and caregivers plan medication refills with confidence. Whether you take daily tablets, liquid medicines, or creams, this tool calculates exactly when your next refill is due and how long your current supply will last.
How It Works
The calculator supports two calculation modes. In Next Refill Date mode, enter your last fill date and days supply (e.g., 30 days for a monthly prescription). The calculator determines your supply end date and next refill date. In Calculate Days Supply mode, enter your total quantity, dosage per dose, and frequency to compute how many days your medication will last.
For tablets and capsules, days supply equals the total tablets divided by tablets per dose times doses per day. For liquid medications, enter the total volume in mL and dose volume per administration. Optionally provide the concentration (mg/mL) to calculate dose volume from your prescribed milligram dose.
If you enter the number of refills remaining, the calculator generates a complete refill timeline showing each future refill date and when each supply period ends. This helps you plan ahead and avoid gaps in your medication regimen.
Regional Notes
India: Prescriptions are typically valid for 6 months to 1 year. Schedule H and H1 drugs require a prescription and have specific record-keeping requirements. Most insurance plans cover 30-day supplies with refill coordination handled by the pharmacy.
US: Medicare Part D and most private insurance plans allow 30-day or 90-day supplies. Controlled substances have strict refill limits — Schedule II drugs cannot be refilled, while Schedule III-V drugs allow up to 5 refills within 6 months of the prescription date.
UK: NHS prescriptions are typically issued for 28 or 30 days. Repeat prescriptions can be ordered online or through your GP surgery. Prescription prepayment certificates (PPC) can save money if you need multiple prescriptions. Some medications may have quantity limits defined by NHS guidelines.
Frequently Asked Questions
How do I calculate my next prescription refill date?
Enter your last fill date and the days supply (e.g., 30 for a monthly prescription). The calculator will add the days supply to your fill date and show the next refill date as the day after your supply ends.
How is days supply calculated for tablets?
Days supply for tablets equals total number of tablets divided by the product of tablets per dose and doses per day. For example, 90 tablets taken as 1 tablet twice daily provides 45 days of supply.
How is days supply calculated for liquid medications?
For liquid medications, the days supply equals total volume in mL divided by the product of dose volume in mL and doses per day. If you know the concentration, enter your prescribed dose in mg and the calculator converts it to volume.
Can I calculate multiple future refill dates?
Yes. Enter the number of refills remaining on your prescription, and the calculator will show a full refill schedule with dates for each future refill and the end date of each supply period.
What is the difference between Rx and OTC medications for refills?
Rx (prescription) medications require a doctor's prescription and typically have a limited number of refills before a new prescription is needed. OTC (over-the-counter) medications can be purchased without a prescription and do not have refill limits.
When should I request a refill?
It is recommended to request a refill at least 3-5 days before your current supply runs out. This accounts for processing time by your pharmacy and any prior authorization requirements from your insurance.
Can I use this calculator for controlled substances?
Yes, but be aware that controlled substances have stricter refill rules. In the US, Schedule II medications cannot be refilled and require a new prescription each time. Schedule III-V medications can have up to 5 refills within 6 months.
How do I calculate days supply for a 90-day prescription?
For a 90-day prescription, the last dose date is your fill date plus 89 days, and your next refill date is the day after your last dose (fill date + 90 days). Always account for varying month lengths when planning refills.