The 1 mg vial

Seven diluent volumes and seven amounts, all worked out for one vial mass. In 2 mL this vial is at most 0.500 mg/mL, which puts 50.0 mcg in each tenth of a millilitre.

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

A 1 mg vial at each diluent volume. Every strength is an upper bound: the solid takes up room once it dissolves, so the finished solution is larger than the diluent and the true strength is this figure or lower.
Diluent	Strength, mg/mL	In 0.1 mL, mcg
0.5 mL	2.000	200.0
1 mL	1.000	100.0
1.5 mL	0.667	66.7
2 mL	0.500	50.0
2.5 mL	0.400	40.0
3 mL	0.333	33.3
5 mL	0.200	20.0

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.

What is particular to a vial this size

The smallest vial on the bench, and the one where the diluent volume matters most. A milligram spread through 5 mL is 200 mcg per millilitre, which makes a 50 mcg amount a quarter of a millilitre - a long, readable draw for a very small quantity. The same milligram in half a millilitre is ten times stronger and the same amount becomes 25 microlitres, which is two and a half units on a U-100 and close to unreadable.

Whole draws a 1 mg vial contains at seven amounts, with what the whole draws leave behind. The count is the arithmetic maximum, not a measured yield: liquid left in the needle, the hub and the vial shoulder is unrecoverable and is not in these figures.
Amount per draw	Whole draws	Exact ratio	Left over
25 mcg	40	40.00	nothing
50 mcg	20	20.00	nothing
100 mcg	10	10.00	nothing
125 mcg	8	8.00	nothing
200 mcg	5	5.00	nothing
250 mcg	4	4.00	nothing
500 mcg	2	2.00	nothing

Reading the two tables together

The first table fixes the strength and therefore the volume of every draw. The second fixes the number of draws and ignores the volume entirely, because how many times an amount divides into a vial has nothing to do with how much liquid the vial was mixed with. A 1 mg vial holds the same number of 100 mcg draws whether it was mixed in half a millilitre or five.

What the diluent volume changes is whether each of those draws is measurable. That is the trade-off the two tables are for: pick the row in the second that gives the draw count you are working with, then pick the row in the first that makes that draw a readable length on the barrel you have.

Why every strength here is a ceiling

Strength is mass divided by the volume of the finished solution, and the finished solution is the diluent plus the room the solid itself takes up. With that displacement unmeasured, dividing by the diluent gives the highest the strength can be rather than the strength it is. Every figure in the first table is that ceiling, which is why it is labelled one.

Measuring the finished volume removes the question. The vial strength tool has a field for it and drops the ceiling label when it is filled in.

Next to this on the bench

The draws-per-vial tool
Any vial, any amount, with the remainder.
The other seven vial strengths
Same two tables, different mass at the top.
Displacement and the ceiling
Why the first table says "at most".