Peptide Reconstitution Math (With Examples)

Every peptide user has stood in front of a vial of BAC water and a freeze-dried peptide vial wondering exactly how many units to draw on the insulin syringe. This post walks through the math with worked examples so you'll never have to second-guess again.

Why the math matters

Peptides are dosed in micrograms (mcg). Insulin syringes are graduated in units. Get the conversion wrong and you've either underdosed or overdosed by a factor of 10.

The formula

units to draw = (desired mcg × syringe units × ml) / (vial mg × 1000)

Or more intuitively: figure out how many mcg are in 1 ml after reconstitution, then how many mcg in 1 unit, then divide your target dose by mcg-per-unit.

Worked example: BPC-157

Vial: 5 mg BPC-157. BAC water added: 2 ml. Target dose: 250 mcg. Syringe: 100-unit insulin syringe (1 ml total).

• 5 mg vial = 5000 mcg total
• 5000 mcg / 2 ml = 2500 mcg per ml
• 1 ml = 100 units, so 1 unit = 25 mcg
• 250 mcg target / 25 mcg per unit = 10 units

Worked example: Ipamorelin

Vial: 5 mg Ipamorelin. BAC water: 2.5 ml. Target: 200 mcg. Syringe: 100u.

• 5000 mcg / 2.5 ml = 2000 mcg per ml
• 1 unit = 20 mcg
• 200 mcg / 20 = 10 units

Worked example: CJC-1295 (no DAC)

Vial: 2 mg CJC-1295. BAC water: 2 ml. Target: 100 mcg. Syringe: 100u.

• 2000 mcg / 2 ml = 1000 mcg per ml
• 1 unit = 10 mcg
• 100 mcg / 10 = 10 units

Choosing your reconstitution volume

Pick a volume that gives you a clean unit number for your standard dose. If you reconstitute a 5mg vial in 2.5 ml of water and your dose is 250 mcg, you'll be drawing 12.5 units (annoying). With 2 ml, the same dose draws cleanly at 10 units.

BAC water vs sterile water

Use bacteriostatic water (BAC water — 0.9% benzyl alcohol). It prevents bacterial growth in the reconstituted vial for up to 28 days. Sterile water has no preservative and the reconstituted peptide must be used within 24 hours.

Skip the math entirely

Use the free reconstitution calculator. Enter vial mg, water ml, and target dose — get exact units to draw with a visual fill diagram. Free, no signup.