The peptide reference library.
Plain-language guides to the math, the materials, and the procedural details behind peptide reconstitution. Cited, neutral, and educational.
From freeze-dried vial to a unit on a syringe
Most research peptides ship as a lyophilized powder inside a sealed glass vial. Before any of that powder can be drawn into a syringe, it has to be dissolved into a sterile diluent at a known concentration — usually bacteriostatic water. The ratio of milligrams of peptide to milliliters of diluent is what determines how many syringe units correspond to a given dose, and that math is where most first-time researchers get tripped up.
The guides below walk through the three pieces that have to line up for a dose to come out right. First, the calculator math itself: vial size, BAC volume, and the resulting concentration in milligrams per milliliter. Second, the syringe: U-100 and U-40 graduations are not interchangeable, and the unit-to-volume conversion changes accordingly. Third, the diluent: bacteriostatic water, sterile water, and saline behave differently once a vial has been opened, and stability windows vary.
Each guide is written for researchers and laboratory professionals working with research-only peptide reference data. Nothing on this site is a dose recommendation, and the content does not address human use, prescribed therapy, or patient self-administration. If you are seeking guidance on therapeutic use of any compound, talk to a clinician — not the calculator.
- Reconstitution 101: from lyophilized vial to syringe unit
How to turn a freeze-dried peptide vial into an exact insulin-syringe dose, the math step by step, and the most common mistakes to avoid.
7 min - Insulin syringe units, decoded
What U-100 and U-40 actually mean, why one mL doesn't always equal 100 units, and how to pick the right syringe for sub-milligram doses.
5 min - Bacteriostatic water vs. sterile water vs. saline
Three diluents, three different stability profiles. When each is appropriate, why benzyl alcohol matters, and what storage rules apply once a vial is reconstituted.
5 min
Reconstitution and syringe questions
- What does it mean to reconstitute a peptide?
- Lyophilized peptides arrive as a freeze-dried powder. Reconstitution is the process of dissolving that powder in a sterile diluent — most commonly bacteriostatic water — to produce a stable solution that can be drawn into a syringe at a known concentration.
- Why are insulin syringes used for peptide injections?
- Most research-peptide doses are well under one milligram. U-100 insulin syringes are graduated in 1-unit increments down to half-unit precision, which is the level of accuracy needed to draw doses on the order of 0.1–0.5 mL. A standard 1 mL or 3 mL syringe is too coarse for sub-milligram volumes.
- Is bacteriostatic water the same as sterile water?
- No. Sterile water is pyrogen-free water with no preservative. Bacteriostatic water adds 0.9% benzyl alcohol, a mild preservative that inhibits bacterial growth and lets a vial be safely drawn from multiple times across roughly 28 days. Saline contains sodium chloride and is isotonic, but is not preserved.
- How long does a reconstituted peptide last?
- Stability depends on the peptide, the diluent, and storage conditions. As a general reference, peptides reconstituted in bacteriostatic water and refrigerated at 2–8 °C are typically considered stable for 28 days, mirroring the labeled use-by date of the BAC water itself. Some peptides degrade faster; check the manufacturer or assay data where available.
- Do these guides give medical advice?
- No. PeptideDose is an educational reference for researchers and laboratory professionals working with peptide reference data. Products covered are research-only. We do not recommend doses, treatments, or off-label use, and the site does not address human use, prescribed therapy, or patient self-administration.
Where to go next
If you already know which peptide you are working with, the peptide library has pre-configured calculators for each one. To work the math from any vial size and BAC volume, jump straight to the reconstitution calculator. For multi-peptide cocktails, see the stacks reference.
PeptideDose is an educational reference. It is not medical advice and does not replace consultation with a licensed healthcare provider. Doses shown in presets are derived from published protocols and product labels — they are not personal recommendations.