How this instrument works
This tool performs one chain of arithmetic: it divides a vial's peptide mass by the diluent volume to get a concentration, divides your target dose by that concentration to get a dose volume, then multiplies the dose volume by 100 to read off the mark on a standard U-100 insulin syringe. It does not calculate, suggest, validate, or bound a dose for any peptide — the target dose is a number you or a prescriber supplies, and the calculator treats it exactly like any other input, whether that number came from a clinical protocol, a research paper, or somewhere else entirely.
The peptides discussed in this context sit on very different legal and regulatory footing, and this calculator takes no position on any of them. Some, like semaglutide and tirzepatide, are FDA-approved prescription drugs when dispensed by a licensed pharmacy under a valid prescription — though both are also sold through unregulated 'research' channels where mislabeled potency and outright counterfeits are documented problems. Others, like BPC-157, are not FDA-approved for any human use at all: the FDA placed BPC-157 on its Category 2 list in 2023, which at the time blocked licensed compounding pharmacies from preparing it, then removed it from that list in April 2026 pending re-review, and in July 2026 an FDA advisory committee voted to recommend allowing it back onto the compounding list — a recommendation still awaiting final FDA action. It's sold online labeled 'for research use only, not for human consumption' because it has never held FDA approval for human use, not solely because of that one Category 2 episode.
Reconstitution itself is a mechanical step common to many injectable peptides and lyophilized (freeze-dried) compounds: a powder in a vial is dissolved in a measured volume of liquid, usually bacteriostatic water, to produce a solution of known strength. Because the resulting concentration depends entirely on how much diluent went in, the same vial can be mixed to very different strengths, and a dose volume calculated for one mixing ratio is wrong for any other — which is the entire reason this arithmetic needs to be redone, carefully, every time either number changes.
The optional cycle fields extend the same arithmetic to supply planning: multiplying a per-dose amount by the number of days in a cycle gives a total mass needed, and dividing that by a single vial's mass gives how many vials that supply requires. Like every other figure here, this is bookkeeping on numbers already decided elsewhere — it doesn't evaluate whether a cycle length or dosing schedule is appropriate for anyone.
- Enter Peptide mass in vial (mg) — the total mass printed on the vial's label, not the volume of liquid inside it.
- Enter Bacteriostatic water added (mL) — the diluent volume actually drawn into that vial during reconstitution.
- Enter Target dose per administration (mcg) — a number you or a prescriber already settled on; this field is not calculated here.
- Read Reconstituted concentration (mg/mL) and Dose volume (mL), then Insulin-syringe draw (U-100 units) for the mark to draw to on a standard U-100 syringe.
- Optional: set Days in this cycle above 0 to also see Total peptide needed for the cycle (mg) and Vials needed for the cycle; leave it at 0 to skip both.
Worked example — one dose, then a full cycle
A vial holds 5 mg of peptide and gets reconstituted with 2 mL of bacteriostatic water, giving a concentration of 5 ÷ 2 = 2.5 mg/mL. A target dose of 250 mcg is 0.25 mg, so the dose volume is 0.25 ÷ 2.5 = 0.1 mL. On a U-100 insulin syringe, 1 mL equals 100 units, so 0.1 mL × 100 = 10.0 units — the mark this dose is drawn to.
Extend the same numbers to a supply question with a different vial: a 10 mg vial reconstituted with 3 mL gives 10 ÷ 3 = 3.33 mg/mL. A 500 mcg (0.5 mg) daily dose from that mix draws to (0.5 ÷ 3.33) × 100 = 15.0 units. Over a 30-day cycle, total peptide needed is 0.5 mg × 30 = 15.0 mg, and vials needed is 15.0 ÷ 10 = 1.5 — in practice, that means buying 2 whole vials of this size to cover the cycle, since a fraction of a vial can't be purchased on its own.
Questions
Does this calculator tell me what dose to take?
No. It performs only the arithmetic that turns a vial's mass, a diluent volume, and a dose you supply into a concentration, a dose volume, and a syringe-unit reading. It has no opinion on what that dose should be for any peptide, condition, or person — that number has to come from somewhere else, and this tool never generates, checks, or bounds it.
Is BPC-157 legal, and is it safe to inject?
BPC-157 is not FDA-approved for any human use. In 2023 the FDA placed it on its Category 2 list, which at the time blocked licensed pharmacies from compounding it. The FDA removed BPC-157 from Category 2 in April 2026 pending re-review, and a July 2026 advisory-committee vote recommended allowing it back onto the compounding list — still awaiting final FDA action, so its status remains unsettled. It's marketed online as 'for research use only' because it has never had FDA approval for human use, not solely because of that listing. This calculator does not evaluate its legality or safety — it only does the reconstitution math if you choose to enter numbers.
Are semaglutide and tirzepatide the same kind of product as BPC-157?
No — they sit on different regulatory footing. Semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) are FDA-approved prescription drugs when dispensed by a licensed pharmacy against a valid prescription. Both are also sold through unregulated 'research' or compounding channels outside that pharmacy system, where mislabeled concentration and counterfeit product are documented risks — a separate concern from the drug's approval status itself.
What is a U-100 syringe, and why does the '100' matter?
U-100 is the standard calibration for most insulin syringes sold in the US: the barrel is marked so that 100 units equals 1 mL, making 1 unit equal to 0.01 mL. That fixed ratio is exactly why the syringe-units formula here multiplies dose volume in mL by 100 — it converts a volume most people can't measure precisely by eye into the marked units a syringe barrel actually displays.
Why does the reconstituted concentration change if I add more or less diluent?
Concentration is vial mass divided by diluent volume, so the same vial mixed with more liquid spreads that mass across a larger volume and reads lower in mg/mL, while less diluent concentrates it higher. A dose volume worked out for one mixing ratio is wrong for any other ratio, which is why the diluent volume actually used has to be entered exactly, not estimated.
What happens if I leave 'Days in this cycle' at 0?
Total peptide needed for the cycle and Vials needed for the cycle both read as 0 and can be ignored — they're an optional supply-planning extension of the same per-dose math, not a separate calculation. Set cycle days above 0 only when you want to see how much total peptide and how many vials a multi-day run of the same dose would require.
Why is 'vials needed' a fraction like 1.5 instead of a whole number?
Vials needed is total mass required divided by a single vial's mass — a pure ratio, so it lands on whatever fraction the math produces. In practice a fractional result like 1.5 means the exact requirement falls between whole vials; since a partial vial generally can't be purchased or reliably measured out on its own, most people round that figure up to the next whole vial to make sure supply doesn't run short.
Can I trust the numbers on the vial and syringe without double-checking them myself?
Treat the vial's printed mass and the diluent volume you actually measured as the two numbers this calculator depends on entirely — if either is wrong, every downstream figure, including the syringe-unit reading, is wrong by the same proportion. Re-reading both figures before entering them, and re-checking the syringe draw against the calculated unit mark, is the same due diligence any measurement-based tool requires.
References
- FDA — Bulk Drug Substances With Significant Safety Risks (BPC-157, Category 2)
- FDA — OZEMPIC (semaglutide) injection, Prescribing Information
- FDA — ZEPBOUND (tirzepatide) injection, Prescribing Information
- NIH/NCBI — Novel Concentrated Insulin Delivery Devices, background on U-100 unit convention (PMC)
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.