Free Tool
Vial Duration Calculator
Enter your vial size, dose, and frequency to estimate how many doses a vial holds and how long it lasts. A general estimate for planning — follow your prescriber's directions.
Enter vial size, dose + frequency, then Calculate.
How Vial Duration Is Calculated
The math is two short steps. First, divide the vial size by your dose and round down to whole doses: doses = floor(vial mg ÷ dose mg). Then spread those doses across your weekly frequency: days = (doses ÷ doses-per-week) × 7.
Worked example: a 10 mg vial dosed at 0.5 mg once weekly gives 10 ÷ 0.5 = 20 doses. At 1 dose per week, that is 20 weeks, or 140 days (20 × 7).
Partial final doses are not counted. If your dose doesn't divide the vial evenly, the leftover amount is shown but excluded from the dose count and run-out date, because it isn't enough for a complete administration. Real-world priming and syringe dead space can leave even less, so treat the result as a planning estimate.
10 mg @ 0.5 mg/wk
20 doses = 140 days ≈ 20 wks
5 mg @ 250 mcg daily
20 doses = 20 days ≈ 2.9 wks
15 mg @ 2.5 mg/wk
6 doses = 42 days = 6 wks
Educational reference only — not a recommendation to use, inject, start, stop, or change any substance or medication. Related: Cost Calculator, Dosing Calculator, or browse all tools.
Frequently Asked Questions
How long will my peptide vial last?
It depends on your vial size, dose per administration, and how often you dose. Divide the vial size (mg) by the dose (mg) to get whole doses, then spread those doses across your weekly frequency. This tool does the math for you, but it is a general estimate — follow your prescriber's directions.
How do I calculate the number of doses in a vial?
Divide the total amount in the vial (in mg) by the size of a single dose (in mg) and round down to a whole number. For example, a 10 mg vial dosed at 0.5 mg gives 20 whole doses. A partial final dose is not counted because there isn't enough left for a full dose.
Why doesn't the calculator count the leftover partial dose?
Only complete doses are counted as usable, because a partial amount left in the vial isn't enough for a full administration. The tool flags any leftover so you know how much remains, but it isn't included in the dose count or the run-out date.
How accurate is the estimated run-out date?
The run-out date assumes you dose exactly on schedule with no missed or doubled doses, and that the full labeled amount is recoverable. Real-world priming, dead space in the syringe, and timing changes can shift the actual date. Treat it as a planning estimate, not a guarantee.
Does my dose unit need to be in mg or mcg?
Either works — use the unit toggle. If you enter your dose in micrograms (mcg), the calculator converts it to milligrams (1 mg = 1000 mcg) before comparing it to the vial size, since vials are labeled in mg.
Is this a substitute for my prescriber's instructions?
No. This is a general estimate for planning and budgeting only, not medical advice. Always follow the dose, frequency, and storage directions provided by your prescriber and pharmacist.
Track vials, reorder timing, doses, and labs in one private timeline — so you never run out unexpectedly.
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