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Peptide Reconstitution Calculator

Enter your vial size, water volume, and desired dose — get the exact draw volume in syringe units instantly. No guesswork, no wasted peptide.

Your Numbers

Dosing Results

Concentration 0mcg/mL
Draw Volume 0mL
Syringe Units 0U-100
Total Doses Per Vial 0doses

Syringe Preview

⚠️ Draw volume exceeds syringe capacity. Use a larger syringe or increase BAC water to reduce concentration.

Vial Duration

Total Doses 0
Days Supply 0 days
⚠️ This exceeds the typical 30-day reconstitution shelf life. Consider using less BAC water for a higher concentration, or splitting into smaller vials.

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Reconstitution 101

Peptides come as a freeze-dried (lyophilized) powder. Here's how to prepare them for injection — step by step.

1️⃣ Gather Your Supplies

You'll need your peptide vial, bacteriostatic water (BAC water), an insulin syringe, and alcohol swabs. Work on a clean surface.

2️⃣ Clean the Vial Tops

Wipe the rubber stopper of both the peptide vial and BAC water vial with an alcohol swab. Let them air dry for a few seconds.

3️⃣ Draw the BAC Water

Using a fresh syringe, draw your desired amount of bacteriostatic water. Common amounts are 1–2 mL. Use the calculator above to determine the best volume for your dose.

4️⃣ Add Water to the Peptide

Insert the needle into the peptide vial at an angle. Let the water trickle down the inside wall slowly — never spray directly onto the powder. This protects the peptide structure.

5️⃣ Swirl Gently — Don't Shake

Once the water is added, gently roll or swirl the vial until the powder is fully dissolved. The solution should be clear. Never shake — agitation can denature the peptide.

6️⃣ Store and Use

Store the reconstituted vial in the refrigerator at 2–8°C (36–46°F). Use within 30 days. Draw your calculated dose with a clean insulin syringe each time.

Frequently Asked Questions

Insulin syringes are marked in units, where 100 units = 1 mL (U-100). To find your mark: take your draw volume in mL and multiply by 100. For example, 0.10 mL = 10 units on the syringe barrel. Hold the syringe horizontally at eye level to read the meniscus accurately. Pull the plunger to the correct unit line, then check again before injecting. The calculator above shows your exact unit count so there's no guesswork.

First, calculate your concentration: divide the vial size (in mcg) by the amount of BAC water you added (in mL). Then divide your desired dose (in mcg) by that concentration. The result is your draw volume in mL. Multiply by 100 to get syringe units on a U-100 insulin syringe. For example, a 5 mg vial reconstituted with 2 mL of BAC water gives a concentration of 2,500 mcg/mL. A 250 mcg dose would be 0.10 mL, or 10 units.

Using too much BAC water lowers the concentration of your solution. This means you'll need to draw a larger volume to get the same dose — which can make small doses hard to measure accurately on a standard syringe. It also increases injection volume, which can cause more site discomfort. Too little water has the opposite problem: very high concentration means tiny draw volumes that are easy to over- or under-pull. The calculator helps you find a middle ground where the draw volume falls in a readable range (10–50 units is ideal for most doses).

Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol, which inhibits bacterial growth. This preservative makes reconstituted peptides stable for up to 30 days in the refrigerator — and it's why multiple-use vials are safe. Sterile water for injection (SWFI) contains no preservative, so a reconstituted vial should be used within 24 hours and discarded. For most peptide protocols that involve daily or twice-daily dosing over weeks, BAC water is the correct choice.

The amount of BAC water depends on the vial size and your preferred concentration. Common choices are 1–2 mL. Less water means a more concentrated solution (smaller injection volume), while more water means a more dilute solution (easier to measure small doses). For a 5 mg vial, 1 mL gives 5,000 mcg/mL; 2 mL gives 2,500 mcg/mL. Choose based on your dose — you want the draw volume to fall in an easy-to-read range on your syringe (typically 10–50 units).

Most reconstituted peptides remain stable for up to 30 days when stored in the refrigerator at 2–8°C (36–46°F). Some peptides may degrade faster. Always check the manufacturer's guidelines. If the solution becomes cloudy or discolored, discard it. Keep the vial away from light and avoid freezing reconstituted peptides. The vial duration calculator above estimates how many days a vial will last at your chosen dose and frequency.

For most peptide doses, a 0.5 mL or 1 mL U-100 insulin syringe works well. Use a 0.3 mL syringe for very small doses (under 30 units) for better accuracy — the smaller barrel means finer graduation marks. A 1 mL syringe is better for larger draw volumes. Always pick the smallest syringe that can hold your full draw volume without exceeding capacity. The syringe toggle in the calculator lets you check which size fits your dose before you draw.

Dosing frequency depends on the specific peptide and the protocol prescribed by your healthcare provider. Common schedules include twice daily (BPC-157), once daily (most research peptides), every other day, or weekly (semaglutide, tirzepatide). Always follow your provider's instructions. This calculator helps you estimate vial duration based on your chosen frequency so you can plan ahead and order refills on time.

IU stands for International Unit — a measure of biological activity rather than weight. It's most commonly used for growth hormone (GH), where 1 IU ≈ 333 mcg. For most other peptides (BPC-157, TB-500, semaglutide, tirzepatide), doses are expressed in micrograms (mcg) or milligrams (mg). This calculator uses mcg for dose input because it's the most precise unit for peptide calculations. If your protocol lists a dose in IU (e.g., GH), check with your provider for the equivalent in mcg before using this calculator.

Reconstitution volume is chosen to match the dose size — not the peptide itself. A low-dose peptide like BPC-157 (250 mcg/dose) reconstituted in 1 mL gives a very small draw volume; adding 2 mL makes it easier to measure. A higher-dose peptide like tirzepatide (2.5 mg dose) reconstituted in 2 mL gives a much larger draw volume. The goal is always to land your draw volume in a range that's easy to read accurately on your syringe — ideally between 10 and 50 units on a U-100 syringe. The calculator lets you adjust water volume and see the effect on draw volume instantly.

Mixing peptides in the same syringe is sometimes done in practice, but it's not generally recommended without guidance from a healthcare provider. Some peptides can interact and degrade each other when combined; others are commonly stacked (e.g., BPC-157 + TB-500). If you do combine, draw each peptide separately into the same syringe rather than mixing in the vial, and use immediately — never pre-mix and store. Always consult with a knowledgeable provider before combining peptides.

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Medical Disclaimer

This calculator is provided for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider before starting any peptide protocol. Peptide use carries inherent risks. The information provided does not constitute a recommendation, endorsement, or prescription. Use at your own risk and under the supervision of a licensed medical professional. Yeager's Gym is not responsible for any adverse effects resulting from the use of this tool.

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