Using the vial longevity calculator.

Two questions come up with every vial: how long will this last, and what is it costing me. Both are arithmetic once you know the strength, the amount per dose, the schedule, and the price.

What it works out.

• •Doses per vial, from strength divided by amount per dose
• •Weeks or months of supply, by applying your schedule to that number of doses
• •Cost per dose, from the vial price divided by usable doses
• •The date the vial runs out, so a reorder is not a surprise

Usable doses versus theoretical doses.

A vial rarely yields exactly what the division suggests. A small residual volume cannot be drawn, some is lost to priming and to the needle hub, and a partial final dose may not be usable. The realistic figure is normally slightly below the theoretical one, so treat the result as the ceiling rather than a promise, particularly when planning the last week before a reorder.

Longevity is not stability.

This calculator answers how many doses are in the vial. It does not answer how long the contents remain fit to use, which is a different question entirely and depends on the compound, the diluent, temperature, light exposure, and handling. A vial can hold eight weeks of doses and have a beyond-use date well short of that. PepCue will not calculate a stability window, because that number would be invented.

Using it to compare vial sizes.

The calculator is genuinely useful for comparing a larger vial against a smaller one at the same amount per dose, since cost per dose often differs more than the headline prices suggest. Just weigh that against the stability question above: a larger vial is only cheaper per dose if you can actually use it inside its usable window.

In the app the same math runs continuously against your logged doses, so days of supply remaining reflects what you actually took rather than what you planned to take.