Enter your vial size, BAC water, and desired dose. Get exact syringe markings instantly.
Save your protocols, log doses, and get reorder reminders — all free.
Download Stackr FreeReconstituting a peptide means adding bacteriostatic water (BAC water) to a lyophilized (freeze-dried) powder to turn it into an injectable solution. Once the peptide is dissolved, you need to know exactly how much solution to draw into your syringe to hit your target dose. That's where this calculator comes in — it takes the three variables that matter (vial size, BAC water added, desired dose) and tells you the precise syringe marking.
The math is simple arithmetic, but the unit juggling between milligrams, micrograms, milliliters, and insulin units is where mistakes happen — and a 10x dosing error with a potent peptide is not something you want to learn from experience. This calculator removes the guesswork.
Example: 10 mg BPC-157 reconstituted with 2 ml BAC water has a concentration of 5,000 mcg/ml. A 250 mcg dose is 0.05 ml, or 5 units on a U100 syringe.
Bacteriostatic water is sterile water containing 0.9% benzyl alcohol as a preservative. The preservative suppresses bacterial growth for up to 28 days after the first puncture, which is why it's the standard diluent for multi-dose peptide vials. Plain sterile water (without preservative) is single-use only — once punctured, the clock starts ticking for microbial contamination.
BAC water is sold in 10 ml, 30 ml, and sometimes larger vials. Store unopened BAC water at room temperature away from light. Once your peptide is reconstituted, store the vial refrigerated.
| Syringe Type | Units per ml | 1 unit equals | Best for |
|---|---|---|---|
| U100 insulin | 100 | 0.01 ml | Most peptides, small doses. US standard. |
| U40 insulin | 40 | 0.025 ml | Veterinary use, some international. Less common. |
| Standard mL | — | — | Oil-based injections like testosterone (TRT). |
The critical mistake to avoid: using a U40 syringe but reading the markings as if it were U100. Every "unit" on a U40 is 2.5× larger than on a U100, so the same "10 units" means a very different dose. Always confirm which syringe you're holding before drawing.
These are dose ranges commonly cited in published research and peptide protocol resources. They are not medical advice — always consult a qualified healthcare professional before starting any peptide protocol.
Need compound-specific guidance? We have dedicated reconstitution guides for tirzepatide, semaglutide, retatrutide, BPC-157, and GHK-Cu — each with vial-specific dose tables and titration schedules.
| Peptide | Typical vial size | Typical dose | Frequency |
|---|---|---|---|
| BPC-157 | 5–10 mg | 250–500 mcg | 1–2× daily |
| TB-500 | 5–10 mg | 2–5 mg | 2× weekly |
| CJC-1295 (no DAC) | 2–5 mg | 100–200 mcg | 1–3× daily |
| Ipamorelin | 2–5 mg | 100–300 mcg | 1–3× daily |
| GHK-Cu | 50–200 mg | 1–2 mg | Daily (topical or injection) |
| Semaglutide | 2–10 mg | 0.25–2.4 mg | 1× weekly (titrated) |
| Tirzepatide | 10–30 mg | 2.5–15 mg | 1× weekly (titrated) |
| Retatrutide | 10–30 mg | 2–12 mg | 1× weekly (titrated) |
Divide your desired dose (in mcg) by the concentration (peptide mcg per ml) to get the draw volume in ml. Multiply by 100 for a U100 insulin syringe to find the insulin-unit marking. This calculator does the math automatically — just pick your vial size, BAC water amount, and dose.
Common amounts are 1 ml, 2 ml, or 3 ml. More water means a lower concentration and larger draw volumes, which can be easier to measure precisely. Less water concentrates the solution into smaller draws. Match the water amount to the syringe size you're using and the precision you need.
U100 is marked so that 100 units = 1 ml (US standard). U40 is 40 units per ml, meaning each unit is 2.5× larger. Using the wrong reading on a U40 vs U100 is the #1 dosing mistake — always confirm which you have.
Most reconstituted peptides in BAC water stay stable for around 28 days refrigerated (36–46°F). Store away from light, avoid freeze-thaw cycles, and discard if you notice cloudiness or discoloration. Some peptides like tirzepatide may remain stable longer.
Yes — the math works for any reconstituted compound. Choose your unit (mg, mcg, or IU), enter your vial size and BAC water, and set your target dose. Works for BPC-157, TB-500, GHK-Cu, CJC-1295, Ipamorelin, Mod GRF, and all GLP-1 analogs.
Switch the dose unit to IU at the top of the calculator. IU is common for HCG, HGH, and insulin. Remember that IU is compound-specific — 1 IU of HCG is not the same mass as 1 IU of HGH — so always use the IU value specific to your compound.
Yes — 100% free, no signup, no ads. For protocol scheduling, dose logging, depletion tracking, and reorder reminders, download the free Stackr iOS app.
This calculator is designed for reconstituted vials. If you use a prefilled pen (Ozempic, Wegovy, Mounjaro, Zepbound, Saxenda), you don't need to reconstitute — the dose is dialed directly on the pen. For compounded semaglutide or tirzepatide from telehealth providers like Hims, Ro, or Mochi, use this calculator since those typically ship as vials with syringes.
Want to save your calculations? The Stackr iOS app remembers your vial sizes, tracks doses, and alerts you before you run out.
Download Stackr FreeStackr is a personal supply and protocol tracking tool. It is not intended to provide medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement, medication, or peptide protocol.