Draws per vial

How many times one figure divides into another, with the leftover named rather than rounded away. The count is a ceiling: what comes out of a vial is always less than what went in.

Educational arithmetic only. Not medical advice and not a dosing protocol.

Fill the fields in and the answer appears here.

What the bench will not tell you

This is educational arithmetic on figures entered by the reader. It is not medical advice, not a dosing protocol, and not a recommendation that anything be prepared, obtained or administered.

Nothing here states what quantity is appropriate for anyone, and there is no function in it that produces an amount to administer. A question about anyone’s health belongs with a licensed clinician who can examine the person asking.

Compounds of the kind this arithmetic is used on are largely research chemicals that are not approved by the FDA for human use. An exact calculation is not an accurate measurement: what is actually in a syringe depends on the preparation and the device, neither of which this page can see.

No qualified clinical reviewer is recorded against this site, and no credential is claimed anywhere on it. the limits of this bench.

The arithmetic, step by step

The exact ratio is one mass over the other, both converted to the same unit first: a 5 mg vial at 250 mcg a draw is 5000 / 250 = 20.
The whole count is that ratio with the fractional part dropped, because two thirds of a draw is not a draw. Five milligrams at 300 mcg is 16.67, which is sixteen.
The remainder is what the whole draws leave: 5000 - 16 × 300 = 200 mcg. It is always smaller than one draw, or there would be another draw in it.

The count is a ceiling and the gap is not small

Arithmetic says a 5 mg vial holds twenty 250 mcg draws. A vial does not. Liquid stays in the needle, in the hub of the syringe and in the shoulder of the vial where a needle cannot reach it, and none of that is recoverable. The real number of full draws is this figure or fewer, never more.

How much fewer depends on the volume, the needle and the vial, none of which this tool can see. What it can do is be clear that the number it prints is the arithmetic maximum rather than a yield anybody measured.

Why the remainder is printed instead of rounded

Because the interesting case is the one where it is nearly a draw. A 10 mg vial at 700 mcg gives fourteen draws with 200 mcg left: not close. The same vial at 1,100 mcg gives nine with 100 mcg left. Knowing which of those two situations you are in is the whole value of the calculation, and a count on its own does not say.

A vial that divides exactly says so. That is worth knowing too: it means the arithmetic has no slack in it at all, so every bit of unrecoverable liquid comes straight off the last draw.

Next to this on the bench

The eight vial strengths
Draw counts tabulated at seven amounts per vial.
Volume for an amount
What each of those draws measures out as.
Strength of a mixed vial
What the vial is at, before dividing.