Peptide Reconstitution Calculator
Enter your vial strength, bacteriostatic water volume, and target research dose. The calculator instantly returns concentration, U-100 insulin syringe units, and doses per vial — with a live syringe visual.
Understanding reconstitution math
Every research peptide arrives as a lyophilized (freeze-dried) powder sealed under vacuum. Before it can be measured accurately, it must be dissolved in a sterile diluent — most commonly bacteriostatic water, which contains 0.9% benzyl alcohol to inhibit microbial growth during repeated draws from the vial.
The math itself is simple, but the implications are not. Once you know the total peptide in the vial and the volume of diluent you added, you know the concentration: micrograms of peptide per milliliter of solution. From that single figure, every subsequent question — how many microliters of solution correspond to a given amount of peptide, how many marks on a U-100 insulin syringe that translates to, how many total doses the vial contains — is a matter of unit conversion.
A U-100 insulin syringe is graduated in units, with 100 units equal to 1 mL. Each single-unit mark therefore represents 0.01 mL. This makes U-100 barrels convenient for reading small volumes precisely, provided you keep the concentration inside a workable range. Very dilute solutions push each draw toward the top of the barrel; very concentrated solutions push each draw into a single-digit unit range that becomes harder to read reliably.
Choosing a diluent volume is therefore a practical trade-off. Adding 1 mL to a 5 mg vial yields 5000 mcg/mL — a compact, concentrated solution. Adding 3 mL yields ~1667 mcg/mL, spreading the same peptide across a larger, easier-to-read volume. Neither is universally correct; the right choice depends on your target amount per draw and how precisely your syringe can resolve it.
Once reconstituted, storage becomes the dominant variable in whether the peptide behaves the same on day 28 as on day 1. Temperature, light exposure, freeze-thaw cycles, and the number of times the septum is punctured all affect stability. For a compound-specific walkthrough of cold-chain handling and refrigerated storage windows, see the cold-chain shipping guide, and for a full workflow of the reconstitution process itself, the research library covers technique and handling in depth.
This calculator is intentionally scope-limited. It converts units. It does not recommend dosing schedules, suggest research protocols, or offer medical guidance of any kind — those decisions belong to the researcher, informed by primary literature, the compound's certificate of analysis, and applicable regulatory frameworks. Use the tool for the arithmetic; use published research for everything else.
Frequently asked questions
›What is peptide reconstitution?
Reconstitution is the laboratory process of dissolving a lyophilized (freeze-dried) peptide powder in a sterile diluent — typically bacteriostatic water — to produce a liquid solution of a known concentration. The concentration is what allows a researcher to measure repeatable volumes for subsequent research applications.
›How much bacteriostatic water should I add to a vial?
There is no single correct volume. Common laboratory choices are 1 mL, 2 mL, 3 mL, or 5 mL per vial. More diluent produces a lower concentration and requires drawing a larger volume per unit of peptide; less diluent produces a higher concentration and a smaller draw. This calculator lets you compare the resulting concentration and syringe units for whichever volume you choose.
›How do you read a U-100 insulin syringe?
A U-100 insulin syringe is graduated in units where 100 units equal 1 mL. Each single-unit mark on the barrel therefore represents 0.01 mL. To convert a volume in mL to units, multiply by 100 — for example, 0.25 mL equals 25 units on a U-100 barrel.
›How should a reconstituted peptide be stored?
Once reconstituted, most research peptides are stored refrigerated at approximately 2–8°C, protected from light, and kept in the original sealed vial. Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits microbial growth in the diluent. Storage temperature, light exposure, and the number of freeze-thaw cycles all affect stability — refer to compound-specific literature.
›What is the shelf life of a reconstituted peptide?
Shelf life after reconstitution is compound-specific and depends on the peptide sequence, diluent, storage temperature, and handling. Many research peptides reconstituted in bacteriostatic water and refrigerated are used within 28 days, though some compounds tolerate longer or shorter windows. Consult the certificate of analysis and the published stability data for the specific compound.