Enter your vial size, water volume, and desired dose — get exact concentration, injection volume, and syringe units instantly.
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Reconstitution Details
Your Reconstitution Results
Step 1 — Concentration: Multiply the vial size in mg by 1,000 to convert to mcg, then divide by the volume of BAC water added in mL.
Step 2 — Draw Volume: Divide your desired dose in mcg by the concentration you just calculated.
Step 3 — Syringe Units: On a U-100 insulin syringe, each graduation equals 0.01 mL. Multiply the draw volume by 100 to get the unit mark to draw to.
Step 4 — Doses Per Vial: Multiply the vial size by 1,000 to get total mcg, then divide by the desired dose size.
Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol, which prevents bacterial growth and keeps reconstituted peptides stable for 4–6 weeks in the refrigerator. It is the standard diluent for peptide reconstitution. Plain sterile water can be used in a pinch but must be used within 24 hours. Never use tap water, distilled water, or normal saline — they can either introduce contaminants or degrade the peptide molecule.
Point the needle at a 45° angle so it hits the glass wall of the vial — not the peptide powder directly. Let the water run slowly down the side and pool at the bottom. Gently swirl (do not shake) until the powder fully dissolves. Shaking denatures the peptide by introducing air bubbles that break down the delicate amino acid chains. The solution may be slightly cloudy at first — wait a few more minutes and swirl again before drawing a dose.
You still get the same total amount of peptide — the concentration just changes. More water = lower concentration = larger draw volume per dose. Less water = higher concentration = smaller draw volume per dose. This calculator handles any combination. Simply enter the exact amount you added, and the results will adjust automatically. The peptide is not wasted either way.
U-100 insulin syringes are calibrated for insulin, where 100 units = 1 mL. That means 1 unit = 0.01 mL. Most peptide users find it easier to work in syringe units rather than mL because the markings are larger and easier to read accurately at small volumes. This calculator converts your dose directly to syringe units — just draw to that number on the barrel.
Reconstituted in bacteriostatic water and stored at 2–8°C (standard refrigerator temperature), most peptides remain stable for 30–60 days. Lyophilized (freeze-dried) powder before reconstitution lasts 1–2 years when kept frozen and away from light. Once reconstituted, avoid freezing — repeated freeze-thaw cycles break down the peptide structure and reduce potency. Always use a new sterile needle each time you draw from the vial to prevent contamination.
Peptides are shipped as a lyophilized (freeze-dried) powder because the dry form is stable at room temperature and survives shipping without degradation. Before you can inject a peptide, you have to dissolve that powder in a liquid — a process called reconstitution. The liquid of choice is bacteriostatic water (BAC water), a sterile solution containing 0.9% benzyl alcohol that inhibits bacterial growth and extends the shelf life of the reconstituted solution to roughly 4–6 weeks when refrigerated.
The math behind reconstitution is straightforward, but the unit conversions trip up almost everyone at first. Vials are labeled in milligrams (mg). Doses are measured in micrograms (mcg). Syringes are marked in milliliters (mL) — or, for insulin syringes, in units where 100 units equals 1 mL. This calculator handles all four unit types so you never have to convert in your head under pressure.
Once you add a known amount of BAC water to a vial of known size, you can calculate everything else. The core formula is:
From the concentration, you work out the draw volume for your specific dose: Desired dose (mcg) ÷ Concentration (mcg/mL) = mL to draw. Then multiply that by 100 to get the unit mark on a U-100 insulin syringe. For a 250mcg dose at 2,500 mcg/mL concentration: 250 ÷ 2,500 = 0.10 mL, which is 10 units on the syringe.
There is no single correct amount of BAC water to add — it depends on your dose size and how easy you want the draw volumes to be. Smaller volumes mean higher concentration and smaller draws (harder to measure accurately). Larger volumes mean lower concentration and larger draws (easier to measure, but the vial runs out faster). The table below shows common configurations:
| Vial Size | BAC Water | Concentration | 250mcg Dose = | 500mcg Dose = |
|---|---|---|---|---|
| 5mg | 1mL | 5,000 mcg/mL | 5 units | 10 units |
| 5mg | 2mL | 2,500 mcg/mL | 10 units | 20 units |
| 5mg | 3mL | 1,667 mcg/mL | 15 units | 30 units |
| 10mg | 2mL | 5,000 mcg/mL | 5 units | 10 units |
| 10mg | 4mL | 2,500 mcg/mL | 10 units | 20 units |
| 2mg | 1mL | 2,000 mcg/mL | 12.5 units | 25 units |
Most users targeting 200–500mcg doses prefer to add 2mL to a 5mg vial. This gives 2,500 mcg/mL — clean, easy numbers that fall between 5 and 20 units on the syringe, which is the easiest range to measure accurately on a standard U-100 insulin syringe.
The technique matters almost as much as the math. Incorrect handling can introduce bacteria, degrade the peptide, or produce an inaccurate dose. Here is the standard protocol:
1. Wipe both vials. Use a fresh alcohol swab on the rubber septum of the peptide vial and the BAC water vial. Let each dry for 10–15 seconds.
2. Draw the water. Insert a sterile syringe into the BAC water vial and draw the exact amount you calculated — 1mL, 2mL, etc.
3. Inject slowly at an angle. Insert the needle into the peptide vial and angle it so the BAC water runs down the glass wall, not directly onto the powder. Slow drip. Do not push hard or fast.
4. Dissolve gently. Remove the needle and gently swirl or roll the vial between your palms. Never shake. Most peptides dissolve clear within 30–60 seconds. If the solution stays cloudy after 2 minutes, continue rolling slowly — some lyophilized powders take longer.
5. Store immediately. Cap the vial and place it in the refrigerator. Write the reconstitution date on the label. Use within 30–60 days for BAC water, or within 24 hours if you used sterile water.
Most peptide users use U-100 insulin syringes (typically 0.5mL or 1mL capacity with 29–31 gauge needles). The syringe is calibrated in "units" where 100 units = 1 mL. Each small graduation on the barrel represents 1 unit = 0.01 mL. Common syringe sizes: 0.3mL (30 units max), 0.5mL (50 units max), 1mL (100 units max). For most peptide doses — which fall between 5 and 50 units — the 0.5mL syringe is easiest to use and read accurately.
The following table lists research-context dose ranges for reference. These are not medical recommendations — always defer to a licensed physician for any dosing protocol.
| Peptide | Common Vial Size | Typical Dose Range | Frequency |
|---|---|---|---|
| BPC-157 | 5mg | 200–500 mcg | 1–2× daily |
| TB-500 | 5mg, 10mg | 2,000–2,500 mcg | 1–2× weekly |
| CJC-1295 (no DAC) | 2mg, 5mg | 100–200 mcg | 2–3× daily |
| Ipamorelin | 2mg, 5mg | 200–300 mcg | 2–3× daily |
| Semaglutide | 2mg, 5mg | 250–1,000 mcg | 1× weekly |
| IGF-1 LR3 | 1mg | 20–100 mcg | Daily or pulsed |
| Selank | 2mg | 100–300 mcg | 1–3× daily |
| Epithalon | 5mg, 10mg | 5,000–10,000 mcg | Cycle-based |
What size syringe should I use for peptides?
A 0.5mL U-100 insulin syringe (50 units capacity) is the best all-purpose choice for most peptide doses. It covers 1–50 unit draws with high precision. If your dose exceeds 50 units, step up to a 1mL (100 unit) syringe. Needle gauge of 29–31G balances ease of injection with minimal tissue trauma. Short needles (5/16" or 8mm) are preferred for subcutaneous injections, which are the standard delivery method for most peptides.
Can I reconstitute a peptide with regular water?
Plain sterile water for injection works but creates a significant practical limitation: once opened, it must be used within 24 hours because it contains no preservative. This makes it unsuitable for multi-dose vials. Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol, which prevents bacterial growth and extends shelf life to 4–6 weeks refrigerated. This is why BAC water is the standard choice for any peptide vial you plan to draw multiple doses from.
How do I know if my reconstituted peptide has gone bad?
Signs of degradation include persistent cloudiness that doesn't clear after gentle swirling, visible particles floating in the solution, discoloration (yellow or brown tint), or an unusual smell. A properly reconstituted peptide should be clear to very slightly opalescent and odorless. If in doubt, discard — the cost of a new vial is minimal compared to the risk of injecting a contaminated solution. Always write the reconstitution date on the label.
Does the amount of BAC water I add change the potency?
No. The total amount of peptide in the vial is fixed — adding more or less water only changes the concentration. More water means a lower concentration and a larger draw volume per dose. Less water means a higher concentration and a smaller draw volume. The peptide molecules themselves are unchanged. This calculator lets you enter any water amount and automatically adjusts the syringe units to maintain your exact intended dose.
What is the difference between subcutaneous and intramuscular peptide injection?
Subcutaneous (SubQ) injection delivers the peptide into the fatty tissue just beneath the skin, typically in the abdomen, thigh, or back of the arm. It produces a slower, more sustained absorption curve. Intramuscular (IM) injection delivers into muscle tissue and absorbs faster. Most peptides — including BPC-157, CJC-1295, Ipamorelin, and semaglutide — are administered subcutaneously. TB-500 can be administered either way depending on the target area. Consult a physician for the appropriate route for your specific protocol.