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Reviewed by the Rite Aid Health Team · Last updated July 9, 2026
Avoid reconstitution mistakes: enter vial size, water, and target dose to get the exact syringe units to draw. Free, no sign-up required.
The calculator Reconstituting your vial How the math works Common reconstitution ratios FAQ
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Peptide in vial
mg
Quick pick:
Bacteriostatic water
mL
Quick pick:
Target dose
Quick pick:
Syringe size
Pick your syringe by barrel size (1 mL, 0.5 mL, or 0.3 mL).
The units to draw are exactly the same whichever one you use. Standard insulin syringes all use the same U-100 math scale.
A smaller barrel just spreads a small dose over more space, making the tiny lines easier to read.
Not sure? Pick 1 mL.
mL
mg/mL
Reconstituting your vial
Reconstitution is adding liquid, almost always bacteriostatic water, to a freeze-dried (lyophilized) peptide so you can measure and inject it.
Clean both stoppers. Wipe the bacteriostatic water vial and peptide vial with alcohol before puncturing either one. Draw the water first. Pull the prescribed amount of bacteriostatic water into the syringe before adding anything to the peptide vial. Add the water slowly. Aim the stream down the inside wall of the peptide vial instead of blasting the powder directly. Swirl gently. Roll or swirl the vial until the powder dissolves. Do not shake it hard. Refrigerate after mixing. Keep the reconstituted vial cold and protected from light unless your prescriber or pharmacy gives different storage instructions.
Get your target dose from a licensed provider — this calculator handles the arithmetic, not the protocol.
How the math works
Your peptide dissolves evenly in the water you add, so the concentration is simply the milligrams in the vial divided by the millilitres of water. Insulin syringes are marked in units, where 100 units equal 1 mL. The three formulas the calculator uses:
Concentration (mg/mL) = vial mg ÷ bacteriostatic water mL Units to draw = (target mcg ÷ (vial mg × 1000)) × water mL × 100 Doses per vial = (vial mg × 1000) ÷ target mcg, rounded down
A 5 mg vial reconstituted with 2 mL of bacteriostatic water is 2.5 mg/mL, or 25 mcg per unit. A 250 mcg dose is 10 units on a U-100 syringe — 0.10 mL. The vial holds 20 doses.
If you only need to convert mcg to mg, mg to mcg, or a substance-specific IU value such as HGH/somatropin or HCG, use the peptide dose converter.
Common reconstitution ratios
Starting points, not recommendations — set your own dose with a clinician. Select a row to load it into the calculator.
Peptide Vial BAC water Concentration Example dose → units (U-100) BPC-157 5 mg 2 mL 2.5 mg/mL 250 mcg → 10 units TB-500 10 mg 3 mL 3.3 mg/mL 2 mg → 60 units Ipamorelin 5 mg 2 mL 2.5 mg/mL 200 mcg → 8 units CJC-1295 2 mg 2 mL 1 mg/mL 100 mcg → 10 units Sermorelin 5 mg 2 mL 2.5 mg/mL 200 mcg → 8 units Tesamorelin 10 mg 2 mL 5 mg/mL 1 mg → 20 units
Get the Free Peptide Tracking Toolkit
One guide for the questions you have now. One workbook for the details you keep.
Excel workbook
11 worksheets for vials, schedules, labs, storage, and more.
PDF guide
Review providers, products, documents, storage, and travel.
Get the free toolkit
Free download
Useful before or after you start
Before you start, compare the details that matter and build a focused question list. Already using peptides? Keep vials, administration, sites, wellness notes, labs, storage, and travel together. Separate your schedule from what actually happened, so important dates are easier to spot. Keep your private working copy on your own device.
Follow the text prompts to receive both downloads and your personal 20% off coupon.
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Reply YES, then send your name and email. We’ll email the download link after confirmation.
For general education only — not medical advice or a treatment recommendation. Peptides are not a substitute for care from a licensed provider. Talk to a qualified healthcare professional before you start, stop, or change any peptide, medication, or supplement.
FAQ
It is the step of adding liquid — almost always bacteriostatic water — to a freeze-dried (lyophilized) peptide so it becomes an injectable solution you can measure in units.
Bacteriostatic water is sterile water with about 0.9% benzyl alcohol added as a preservative. The benzyl alcohol stops bacterial growth, which is what lets a reconstituted vial be used across multiple doses over several weeks in the fridge. It is the standard diluent for reconstituting peptides.
Sterile water and bacteriostatic water both dissolve the peptide, but sterile water has no preservative, so a vial mixed with it is meant for a single use and should not be stored. Bacterial-growth risk is why bacteriostatic water is preferred for multi-dose vials. Follow the diluent your prescriber or the product labeling specifies.
Enough to make your dose easy to measure without overfilling the syringe. More water spreads the dose across more units for finer control; less water concentrates it into fewer units. Common volumes are 1 to 3 mL. The amount you add does not change the total peptide in the vial — only how many units each dose works out to.
The vial always holds the same amount of peptide. Adding more water spreads that peptide through a larger volume, so each microgram sits in more millilitres — and more units — of solution. That is why 5 mg in 1 mL reads as half the units of 5 mg in 2 mL for the same dose. It changes the measurement, not the dose.
That depends on three things: the milligrams in your vial, how much bacteriostatic water you added, and your target dose. Enter all three above and the calculator gives the exact unit mark for your syringe.
1 mg equals 1,000 mcg. So a 5 mg vial contains 5,000 mcg, and a 250 mcg dose is 0.25 mg. The calculator accepts either unit for your target dose — switch the mcg/mg toggle next to the dose field.
Choose by barrel size — 1 mL (100-unit), 0.5 mL (50-unit), or 0.3 mL (30-unit). They all use the same U-100 scale, where 1 unit equals 0.01 mL, so a given dose is the same number of units on any of them; only the total capacity and how far apart the ticks sit differ. A smaller barrel spreads a small dose across more length, making it easier to measure accurately.
Round to the nearest half or whole unit you can read reliably, or reconstitute with a different amount of water so the dose lands on an easier mark. If you routinely land between ticks, a smaller-barrel syringe or a more dilute mix makes the dose easier to measure. Confirm any change with your provider.
Refrigerated at 2–8 °C, most are stable for roughly 28 days; some are shorter. Keep the vial cold, protect it from light, and never share needles. Always follow the storage guidance for your specific peptide.
No. It converts a dose you have already been given into syringe units — it does not set your dose, confirm a peptide is appropriate for you, or replace a clinician. Get your target dose and protocol from a licensed provider.