How to Calculate Peptide Reconstitution: The Simple Math

Reconstitution math intimidates more people than it should. There are three variables. There is one formula. Once you understand it, you never have to think about it again.

The three variables

1. Peptide weight in the vial — usually in milligrams (mg). Printed on the vial.
2. Volume of bacteriostatic water you add — your choice, usually 1–3 ml.
3. Target dose per injection — usually in micrograms (mcg) for most research peptides.

The formula

Units on the syringe = (target dose ÷ peptide weight) × (BAC water volume × 100)

The "×100" converts from milliliters to insulin-syringe units. A standard insulin syringe is 100 units = 1 ml.

Worked example

You have a 5 mg BPC-157 vial. You add 2 ml of bacteriostatic water. Your target dose is 250 mcg.

• target dose ÷ peptide weight = 250 mcg ÷ 5000 mcg = 0.05
• BAC water volume × 100 = 2 × 100 = 200
• Units on syringe = 0.05 × 200 = 10 units

So you draw to the 10-unit mark on your insulin syringe.

Why the same dose looks different across people

Two people on "250 mcg of BPC-157" can pull radically different unit counts. Why? Because they reconstituted with different amounts of BAC water. With 1 ml of water that 250 mcg dose is 5 units; with 3 ml it is 15 units. The amount of peptide is identical — only the concentration changes.

This is also why the question "how many units should I take?" has no answer without knowing the vial weight and the water volume.

The shortcut everyone wants

• Choose your BAC water volume first based on the syringe units you find easy to read (10–30 units works for most people).
• Plug into the formula once.
• Write the result on a sticker on the vial.
• Save it in Peptide IA so it auto-fills the next time you log.

Common reconstitution mistakes

• Squirting BAC water directly onto the peptide pellet. Always run the water down the inside wall of the vial. Foaming damages the peptide.
• Shaking the vial. Swirl gently, do not shake.
• Using regular saline. Use bacteriostatic water (water with 0.9% benzyl alcohol). Plain saline is not preserved and grows bacteria.
• Forgetting the vial date. Once reconstituted, most peptides are stable refrigerated for ~30 days. After that, half-life is your enemy.

A note on accuracy

Insulin syringes are not laboratory instruments. A 0.5-unit difference is within normal user error. Do not chase decimal-point precision; chase consistency. The same person drawing the same dose the same way each day produces useful data. Trying to hit 12.7 units instead of 13 does not.

What the calculator does for you

A good reconstitution calculator removes the formula from your daily life. Enter the vial spec once when you reconstitute, save the protocol, and from then on log doses by name — not by math.

Peptide IA is an educational and self-tracking tool. Nothing in this post is medical advice. Doses mentioned reflect what is commonly reported in research literature — they are not recommendations. Always consult a qualified physician before starting, changing, or stopping any protocol.