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Vial duration calculator
Enter the vial's peptide mass, the amount you draw per entry, and how often you draw it. The calculator returns how many entries the vial contains and roughly how long that lasts — which is what you need in order to reorder before running out, not after.
How it works
entries = floor(vial amount ÷ amount per entry)— you cannot draw a partial entry from an empty vial.days = entries × interval in days, then projected onto a calendar from your start date.- Where a vial's in-use window is shorter than the projected duration, that window is the real constraint.
Why this matters more than it sounds
- Reordering. Shipping is not instant, and running out mid-schedule is a break you then have to record and explain.
- Large vials. GHK-Cu at 100 mg and NAD+ at 1,000 mg last long enough that the in-use window is usually the binding constraint.
- Dead space. A small volume is retained in the syringe and needle hub, so the final theoretical entry often is not fully drawable.
- Budgeting. Cost per entry is vial cost ÷ entries, which is a more useful figure than cost per vial.
PepCycle tracks remaining contents automatically as entries are logged — including backdated ones — and can notify you before a vial runs low, which is the version of this that does not require you to remember to check.
Frequently asked questions
How many doses are in a 5 mg vial?
It depends entirely on how much you draw each time. A 5 mg vial is 5,000 mcg, so at 250 mcg per entry it holds twenty entries; at 500 mcg it holds ten. Enter your own figures above.
Why does my vial run out earlier than calculated?
Usually dead space — the small volume retained in the syringe and needle hub after injection — which means the last theoretical entry often cannot be fully drawn. Small measurement variations across many entries add up as well.
Should I use a vial past its in-use window if there is peptide left?
The in-use window and the remaining contents are independent, and the window is there for stability and sterility reasons rather than to be economical with. Follow the supplier's or pharmacy's stated window.
Related pages
Stop recalculating this every time
PepCycle stores each vial once — mass, diluent volume, concentration — and converts automatically for every entry after that, in both directions, including entries you backdate.
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