Enter your vial size, dose per injection, and how often you inject — see exactly how many doses are left and when you'll need a refill. For cost forecasting across a full protocol with multiple compounds, see the full Cost & Run-Out Planner.
Vial longevity calculator
A one-off calculation — nothing here is saved or sent anywhere.
How to Use This Calculator
Four numbers tell you exactly how long a vial will last.
Enter your vial sizeCheck your vial label for total mg content — this is the whole vial's supply, not a single dose.
Enter your per-injection doseThe amount you actually inject each time, in mg or mcg.
Enter your injection frequencyHow many injections per week your protocol calls for — daily is 7, twice weekly is 2, and so on.
Optionally add a start dateIf you enter the date you opened (or plan to open) the vial, the tool calculates an actual calendar run-out date, not just a duration.
How the Math Works
Straightforward division — the same calculation behind any "how long will this last" question.
Total doses in the vial. Doses per vial = vial size (mg) ÷ dose per injection (converted to the same unit) — rounded down, since a partial dose isn't a usable full dose. Basic arithmetic; floor rounding since fractional doses can't be drawn as complete injections.
Days and weeks of supply. Days of supply = total doses ÷ injections per week × 7. Weeks of supply = days ÷ 7. Direct conversion from dose count and frequency.
Run-out date. If a start date is provided, the run-out date is simply the start date plus the calculated days of supply. Standard date arithmetic.
Estimate only — not medical advice. This tool calculates supply duration based on numbers you enter — it does not account for wasted doses (draw error, spilled or discarded partial doses), vial beyond-use/discard dates, or any change in your dose or frequency over time. For discard timing specifically, see the Medication Storage Calculator — a vial can run out on the calendar before it's actually empty.
Frequently Asked Questions
Why does this show fewer doses than a simple division would suggest?
Doses per vial is intentionally rounded down — a partial dose isn't a complete usable injection, so the count reflects how many full doses the vial can actually deliver.
Does this account for the vial's beyond-use or discard date?
No — this tool only calculates how long the vial's contents would last based on dose size and frequency. A vial can reach its discard date before it's empty, especially at low doses or infrequent dosing. Check the Medication Storage Calculator for that separately, since supply duration and safe-use duration are two different questions.
What if my frequency isn't a whole number, like every 10 days?
Enter it as injections per week using a decimal (e.g. every 10 days ≈ 0.7 injections per week) — the calculator handles fractional frequencies correctly.
Can I use this for a titrating dose schedule where the amount changes over time?
This tool assumes a constant dose throughout — it will give you an estimate based on whatever single dose you enter. For a schedule where the dose changes over time (like GLP-1 titration), see the GLP-1 Titration Planner, which accounts for dose changes.
Why is my run-out date important to know in advance?
Running out mid-protocol can mean an unplanned gap in dosing, which for some compounds (especially those on a strict weekly schedule) can affect consistency. Knowing your run-out date ahead of time gives you a buffer to reorder or refill.
Does this calculator account for wasted or spilled doses?
No — it assumes every dose drawn is used exactly as calculated, with no loss. Real-world use often has minor variance (dead space in syringes, occasional spillage), so actual supply may run out slightly earlier than this estimate.
What's the difference between this and the Cost & Run-Out Planner in the full app?
This standalone tool does a single one-off calculation for one vial. The full Cost & Run-Out Planner handles multiple compounds and cycles at once, factors in cost per dose, and (in the full app) tracks your actual inventory over time rather than a hypothetical scenario.
Does this tool save my numbers anywhere?
No — everything runs locally in your browser. To track your actual inventory and get automatic low-stock alerts, see the full Peptide Plug app.
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