How to Use This Calculator
This calculator removes the math from peptide reconstitution. You enter three things — the amount of peptide in your vial, how much bacteriostatic water you're adding, and your target dose — and it tells you exactly which mark to draw to on a standard insulin syringe.
A worked example: you have a 10 mg vial of BPC-157. You add 3 ml of bacteriostatic water. Your target dose is 250 mcg. The calculator returns: draw to the 7.5 unit mark on a 0.5 ml insulin syringe (which equals 0.075 ml of solution). The on-screen syringe diagram shows the exact line.
Once you have a calculation that works, click Copy Shareable Link and the URL preserves your inputs. You can save it, send it to a research partner, or bookmark it for repeat reference. The calculator works with any peptide in our full catalog, plus custom values for compounds we don't carry.
What Is Bacteriostatic Water and Why It Matters
Bacteriostatic water is sterile water with 0.9% benzyl alcohol added as a preservative. The benzyl alcohol prevents bacterial growth in the vial after the peptide is reconstituted, which is what makes multi-day storage of injectable solutions possible. Plain sterile water has no preservative, which means a reconstituted vial would need to be used within hours, not weeks.
For most research peptides, bacteriostatic water is the appropriate diluent. It's mildly acidic (pH around 5), which helps maintain the stability of most peptide structures. The exceptions are highly hydrophobic peptides that don't fully dissolve in water — those may require a small amount of acetic acid or a specific buffer.
The volume of bacteriostatic water you choose is a practical decision, not a chemistry one. Adding 1 ml versus 3 ml to the same 10 mg vial gives you the same total amount of peptide — you're just changing the concentration. More water means a larger draw volume on the syringe, which is easier to measure accurately for small doses. Less water means a smaller draw, which is easier when you want to inject minimal volume but harder to measure precisely.
A practical guideline: aim for a reconstitution volume that puts your target dose somewhere between 5 and 30 units on a standard insulin syringe. That range is easy to read accurately. The calculator will flag if your inputs result in a draw smaller than 1 unit (hard to measure) or larger than your selected syringe (won't fit).