Tools

Reconstitution calculator

Vial size, water added, and the amount you want. It returns the concentration and the syringe units, and prints every step so you can check it rather than trust it.

Peptide in vial

Bacteriostatic water added

Amount you want

mcg

Syringe

Concentration

5,000 mcg/mL

Draw volume

0.1 mL

Syringe units

Doses per vial

Draw to 10 units on a 1 mL insulin syringe for 500 mcg.

The working, so you can check it

1. Concentration = 10 mg / 2 mL = 5 mg/mL
2. Convert first: 500 mcg / 1000 = 0.5 mg
3. Volume = 0.5 mg / 5 mg/mL = 0.1 mL
4. Units = 0.1 mL x 100 = 10 units

Step 2 is the one people skip. Dividing 500 by 5 without converting gives 100, which is 1,000 times too much. Every insulin syringe is U-100, so 100 units is 1 mL on all three barrel sizes. Picking a smaller barrel does not change the number, it spreads the same marks further apart and makes a small draw easier to read.

Arithmetic only. This converts between mass and volume and nothing else. It does not know what is in your vial, and it has no opinion on whether any amount is sensible. A number being calculable is not evidence that it is a good idea.

The one mistake this exists to prevent

Milligrams and micrograms are mass. Syringe units are volume. They have nothing to do with each other, and mixing them up is how people end up ten or a thousand times off with a perfectly good vial.

A 10 mg vial in 2 mL of water is 5 mg/mL. Wanting 250 mcg from it means converting to 0.25 mg first, then dividing. Skip the conversion, divide 250 by 5, and you get 50 units instead of 5. That is the error, and it is why the conversion line is always shown above rather than done quietly.

More water is not weaker

The vial holds the same amount however much water goes in. What changes is how easy the amount you want is to measure. The same target can land on 2.5 units, 5 units or 7.5 units depending on the water, and only one of those is a mark you can actually read. That is the only reason to prefer one volume over another.

This page only discusses dilution arithmetic. It is not medical advice, and it is not a recommendation to use any particular substance. Nothing on this page has been evaluated by the FDA.