Peptide reconstitution calculator

How much BAC water to add to a peptide vial

There is no single right amount: the water only decides how strong the mix is, and so how many syringe units each dose takes. Most people choose 1 to 3 mL so that their usual dose lands on a mark between about 5 and 50 units. More water makes small doses easier to read; less water keeps large doses inside one syringe.

Find your vial in the table and read across: each cell is the strength that volume gives and what 10 units on a U-100 syringe then holds. If you know the units you want each dose to be, the reverse calculator above gives the exact volume.

• 5 mg + 2 mL = 2.5 mg/mL → 10 units = 250 mcg
• 10 mg + 2 mL = 5 mg/mL → 10 units = 500 mcg
• 10 mg + 4 mL = 2.5 mg/mL → 10 units = 250 mcg

How to mix peptides with bacteriostatic water

Mixing (reconstituting) a lyophilised peptide takes a couple of minutes. The goal is to dissolve the powder without foaming or contaminating the vial, and to write down exactly how much water you added, because every dose calculation depends on it.

• Let the vial and the water reach room temperature; wash your hands
• Wipe both rubber stoppers with an alcohol swab and let them dry
• Draw the planned volume of bacteriostatic water into a sterile syringe
• Insert the needle into the peptide vial and let the water run slowly down the inside wall, not onto the powder
• Swirl or roll the vial gently until clear; do not shake it
• Label the vial with the date and the water added, then refrigerate

How long do reconstituted peptides last?

It depends on the product, and the label always wins. For approved medicines the limit is printed: Egrifta SV (tesamorelin) is used immediately after mixing, Egrifta WR is kept at room temperature and discarded after 7 days, Genotropin (somatropin) cartridges keep up to 28 days in the fridge, and hCG lasts 30 days (Novarel) or 60 days (Pregnyl) refrigerated.

Research peptides have no label, so there is no tested shelf life after mixing. Keep the vial in the fridge at 2–8 °C, protected from light, never freeze it once mixed, and follow your supplier's or pharmacy's beyond-use date. In clinics, opened multi-dose vials are generally discarded 28 days after first use unless the manufacturer says otherwise.

See also: Tesamorelin calculator · HGH IU calculator · HCG reconstitution calculator

How peptide reconstitution math works

Reconstitution math starts with concentration. The total peptide in the vial is divided by the amount of diluent added, which tells you how much peptide is present in each mL.

Once concentration is known, the target dose is divided by that concentration to calculate the draw volume. Syringe units are then derived from the syringe scale.

• Concentration = total peptide / diluent volume
• Dose volume = target dose / concentration
• U-100 units = mL to draw x 100

5 mg vial with 2 mL BAC water example

A 5 mg vial contains 5,000 mcg total. If you add 2 mL of diluent, the concentration is 2,500 mcg/mL.

At that concentration, a 250 mcg target dose is 0.1 mL. On a U-100 syringe, 0.1 mL equals 10 units.

• 5 mg = 5,000 mcg
• 5,000 mcg / 2 mL = 2,500 mcg/mL
• 250 mcg / 2,500 mcg per mL = 0.1 mL = 10 U-100 units

10 mg vial with 2 mL BAC water example

A 10 mg vial contains 10,000 mcg total. Mixed with 2 mL, the concentration is 5,000 mcg/mL.

At that concentration, a 500 mcg target dose is 0.1 mL, which is 10 units on a U-100 syringe. A 250 mcg target dose would be 0.05 mL, or 5 U-100 units.

• 10 mg = 10,000 mcg
• 10,000 mcg / 2 mL = 5,000 mcg/mL
• 500 mcg / 5,000 mcg per mL = 0.1 mL = 10 U-100 units

Why do peptide calculators give different answers?

A common frustration is entering the same vial and dose into two calculators and getting two results. It usually is not a bug — it is that one tool assumes a different diluent volume, a different syringe scale (U-100 vs U-40), or rounds the draw to the nearest unit while the other does not.

Concentration itself is not ambiguous: total peptide divided by diluent volume is fixed. Disagreements come from the assumptions layered on top. This calculator shows the concentration, the exact mL, and the syringe units side by side so you can see which assumption a different tool made, rather than trusting a single rounded number.

• Same vial + same dose should give the same concentration — always
• Differences trace to diluent volume, syringe scale, or rounding
• Check the syringe type (U-100 has 100 units/mL) before comparing units

When to use this calculator

Use this page before the first draw from a newly mixed vial or whenever vial strength, water volume, target dose, or syringe type changes.

If you already know the concentration and only need mL or units for a dose, the peptide dose calculator is the more direct tool.