Peptide reconstitution calculator
Enter a vial strength, how much bacteriostatic water you are adding, and the dose you want to measure. The calculator returns the concentration, the volume to draw, and the exact mark on an insulin syringe, and shows it on a live syringe.
Results
- Concentration
- 5.00 mg/mL
- Volume to draw
- 0.100 mL
- Doses per vial
- 20
- Per single unit
- 50.0 mcg
Three lines of arithmetic
There is no pharmacology in this calculator. It is unit conversion, and it is worth understanding rather than trusting blindly, because a misplaced decimal here is the single most common measurement error in peptide handling.
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Concentration
Vial strength ÷ diluent volume. A 10 mg vial in 2 mL gives 5 mg/mL. The water does not dilute the drug away. The same 10 mg is simply spread through more liquid.
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Draw volume
Dose ÷ concentration. A 500 mcg (0.5 mg) dose at 5 mg/mL needs 0.1 mL.
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Syringe units
Volume × 100. 0.1 mL is 10 units on any U-100 insulin syringe, because all of them are marked 100 units to the millilitre.
More water is not a weaker dose
This trips people up constantly. Adding 3 mL instead of 1 mL does not reduce the amount of peptide you draw. It just means you draw a larger volume to get the same quantity. Larger volumes are easier to measure precisely, which is the real argument for using more diluent when the barrel allows it.
What this tool deliberately will not do
It will not suggest a dose, a frequency, a duration or a route. Those are clinical decisions that depend on the compound, the person and the indication, and for most compounds discussed online, there is no established human dose at all because no adequate trial has ever been run.
The same dose, four concentrations
A 500 mcg dose drawn from a 10 mg vial, reconstituted four different ways. The quantity of peptide is identical every time; only the volume and the syringe mark change.
| Diluent added | Concentration | Volume for 500 mcg | Syringe units | Doses in the vial | Practical note |
|---|---|---|---|---|---|
| 1 mL | 10 mg/mL | 0.05 mL | 5 units | 20 | Hard to measure accurately, small errors matter a lot |
| 2 mL | 5 mg/mL | 0.10 mL | 10 units | 20 | Comfortable on any barrel |
| 3 mL | 3.33 mg/mL | 0.15 mL | 15 units | 20 | Good resolution; needs a 30-unit barrel or larger |
| 5 mL | 2 mg/mL | 0.25 mL | 25 units | 20 | Best resolution, but more volume and faster vial turnover |
Reconstitution, answered
There is no fixed answer. It depends entirely on concentration. From a 10 mg vial in 2 mL (5 mg/mL), 500 mcg is 10 units. From a 5 mg vial in 2 mL (2.5 mg/mL), the same 500 mcg is 20 units. Any answer given without stating the concentration is meaningless, which is exactly why this calculator asks for the vial strength and diluent volume first.
Bacteriostatic water is sterile water containing roughly 0.9% benzyl alcohol, a preservative that inhibits bacterial growth. That allows a vial to be punctured repeatedly over days or weeks. Plain sterile water has no preservative and is intended for single use. The choice affects how long a reconstituted solution can reasonably be kept, not the arithmetic of the dose.
Because the concentration is too low for the dose you asked for. A 1 mg vial diluted into 3 mL gives 0.33 mg/mL, so a 1 mg dose would need 3 mL, three full 100-unit barrels. Using less diluent raises the concentration and brings the volume back within range. The calculator flags this rather than silently showing an impossible number.
For the quantities involved here, no. A few milligrams of lyophilised peptide displaces a negligible volume relative to 1 to 5 mL of diluent, well under the measurement error of the syringe itself. This is why reconstitution calculators universally treat the final volume as equal to the diluent volume.
No. It performs arithmetic on numbers you supply, in the same way a unit converter does. Whether a given compound has any established human use, what dose would be appropriate, and whether it is legal to obtain are entirely separate questions, and for most compounds sold as “research peptides”, the honest answer to the first is that no adequate human trial exists. The peptide directory grades the evidence for each compound individually.
Know what you are measuring
The arithmetic is the easy part. What the compound actually does, and whether anyone has ever tested it properly in humans, is the part worth your time.
- Every entry graded
Four evidence tiers, applied consistently and dated.
- Real citations
PubMed and trial-registry identifiers, not vague gestures at “studies”.
- Nothing for sale
No products, no affiliate links, no sponsored entries.