18+ · Research Use Only · Not for Human Consumption
Peptide reconstitution math: three formulas, fully worked.
Every question about vials, water and syringe units reduces to three short calculations. Learn them once and no online calculator is ever needed again.
Formula one: concentration
Concentration in mg/ml equals milligrams in the vial divided by milliliters of bacteriostatic water added. A 10mg retatrutide vial with 2ml reads 5 mg/ml. A 20mg BPC-157 vial with the same 2ml reads 10 mg/ml. The vial mass is fixed at purchase; the water volume is the one variable you control, and it should be measured with the syringe, not estimated. Write the result on the label immediately, because every later calculation depends on it.
Formula two: micrograms per unit
One unit on a U-100 insulin syringe is 0.01ml. Micrograms per unit therefore equals mg/ml times ten: at 5 mg/ml a unit holds 50 mcg, at 10 mg/ml it holds 100 mcg. The full derivation and syringe sizing notes are in the syringe units post. Worked across the catalogue:
| Vial + water | Concentration | Per unit |
|---|---|---|
| Retatrutide 10mg + 2ml | 5 mg/ml | 50 mcg |
| BPC-157 20mg + 2ml | 10 mg/ml | 100 mcg |
| TB-500 5mg + 1ml | 5 mg/ml | 50 mcg |
| CJC/Ipamorelin 5mg+5mg + 2ml | 5 mg/ml | 50 mcg |
| GHK-Cu 50mg + 2.5ml | 20 mg/ml | 200 mcg |
Formula three: units for a target draw
Units equals the target quantity in micrograms divided by micrograms per unit. A 500 mcg laboratory aliquot from the retatrutide preparation above: 500 divided by 50 is 10 units. A 250 mcg aliquot from the BPC-157 preparation: 250 divided by 100 is 2.5 units, an awkward half-mark read. That awkwardness is a planning signal, not a measuring problem: reconstituting the same 20mg vial with 4ml instead of 2ml halves the concentration to 5 mg/ml, and the same 250 mcg draw becomes a clean 5 units. Run formula three before you reconstitute, not after, and pick the water volume that puts your expected draws on whole marks. The mixing table lists the volume options per vial. One sanity check catches most errors: total units in the vial equals milliliters times 100, so a 2ml preparation holds 200 units, and your per-draw figure times expected draw count should not exceed it.
Supplied for laboratory research use only. Not for human consumption. Nothing on this page is medical advice.
Reconstitution math questions
What is the basic reconstitution formula?
Concentration in mg/ml equals milligrams of peptide in the vial divided by milliliters of bacteriostatic water added. A 10mg vial with 2ml gives 5 mg/ml. That one number drives everything else.
How do I convert mg/ml to micrograms per syringe unit?
Multiply the mg/ml figure by ten. One U-100 unit is 0.01ml, so 5 mg/ml means 50 mcg per unit and 10 mg/ml means 100 mcg per unit. The factor of ten comes straight from the 0.01ml unit volume.
How do I work out units for a target quantity?
Divide the target in micrograms by the micrograms per unit. A 500 mcg laboratory aliquot at 5 mg/ml, which is 50 mcg per unit, is 500 divided by 50, so 10 units. If the answer lands on a fraction the barrel cannot show, reconstitute with more water next time so the draw lands on a readable mark.
How many draws does one vial contain?
Divide the vial mass by the aliquot mass, water volume does not change it. A 10mg vial split into 250 mcg aliquots gives 40 draws whether it was reconstituted with 1ml or 3ml. Volume only changes how many units each draw spans.