How to Reconstitute Peptides: Step-by-Step Guide with Dosage Calculator

What You Need

Do NOT use: Regular sterile water (no preservative — bacteria can grow), saline (can degrade some peptides), or distilled water (not sterile).

Step-by-Step Reconstitution

1. Gather supplies — peptide vial, BAC water vial, insulin syringe, alcohol swabs. Work on a clean surface.
2. Swab both vial tops — wipe the rubber stopper on both vials with an alcohol swab. Let dry for 15 seconds.
3. Draw BAC water into syringe — insert the needle through the BAC water vial stopper at an angle; draw back the plunger to pull in your desired volume (see dose calculator below). Typically 1–2 mL per vial.
4. Inject BAC water slowly into peptide vial — insert needle through the peptide vial stopper and drizzle the water slowly down the side of the vial. Do NOT squirt directly onto the powder — this can damage the peptide structure.
5. Swirl gently — do not shake — hold the vial between two fingers and gently rotate until the powder is fully dissolved. The solution should become completely clear. Shaking introduces bubbles and can denature the peptide.
6. The solution is ready — store in refrigerator immediately. Most reconstituted peptides are stable for 4–6 weeks refrigerated.

Dose Calculation: The Math

This is where most people get confused. The formula is simple once you see it once:

Formula: (Dose in mcg ÷ Total mcg in vial) × Volume of BAC water added (in mL) × 100 = Units to draw on insulin syringe

Example — BPC-157 250 mcg dose:

• Vial contains: 5,000 mcg (5 mg)
• BAC water added: 2 mL
• Desired dose: 250 mcg
• Calculation: (250 ÷ 5,000) × 2 × 100 = 10 units on the syringe

Example — Ipamorelin 200 mcg dose:

• Vial contains: 2,000 mcg (2 mg)
• BAC water added: 2 mL
• Desired dose: 200 mcg
• Calculation: (200 ÷ 2,000) × 2 × 100 = 20 units on the syringe

Tip: Using 1 mL of BAC water makes the math easy for some peptides (every 10 units = 10% of the vial), but 2 mL gives you more precision at small doses and is generally preferred.

Storage and Shelf Life

• Unreconstituted (lyophilized) powder: Refrigerator for months; freezer for 1–2 years. Keep away from light.
• Reconstituted solution: Refrigerator at 36–46°F (2–8°C) for 4–6 weeks. Some peptides (BPC-157, TB-500) are more stable; more sensitive peptides (CJC-1295 without DAC, ipamorelin) should be used within 4 weeks.
• Do not freeze reconstituted peptides — freeze-thaw cycles degrade the solution.
• Discard if: The solution becomes cloudy, changes color, or you see particles. This indicates degradation or contamination.

Injection Technique

Most research peptides are administered subcutaneously (SubQ) — injected into the fatty tissue just below the skin, not into muscle (intramuscular/IM).

• Common injection sites: Abdomen (1–2 inches from navel), outer thigh, or upper arm fat. Rotate sites to avoid lipodystrophy (fat atrophy at injection site).
• Technique: Pinch the skin to lift the fat layer. Insert the needle at a 45-degree angle (or 90 degrees if you have adequate fat). Inject slowly. Release the pinch. Apply gentle pressure with a swab after — don't rub.
• Needle size: 28–31 gauge, 5/16–1/2 inch (8–12 mm). Standard U-100 insulin syringes work perfectly.

Common Reconstitution Mistakes

Even experienced peptide users make these errors. Avoiding them protects your investment and your health.

1. Using the wrong water. Sterile water (without preservative) is acceptable for single-use vials, but most peptide vials are multi-dose — meaning you'll puncture the stopper multiple times over weeks. Without the 0.9% benzyl alcohol preservative in bacteriostatic water, bacteria can colonize the vial after the first needle entry. Always use BAC water for multi-dose peptide vials. Distilled water is not sterile and should never be injected.
2. Not calculating concentrations properly. Adding 1 mL vs 2 mL of BAC water to the same vial creates drastically different concentrations. A 5 mg BPC-157 vial with 1 mL = 5,000 mcg/mL; with 2 mL = 2,500 mcg/mL. If you don't recalculate your syringe units after changing the water volume, you'll dose incorrectly — potentially doubling or halving your intended dose.
3. Shaking the vial instead of swirling. Peptides are fragile protein chains. Vigorous shaking creates foam, introduces air bubbles, and can physically denature (break apart) the peptide through shear forces. Always swirl gently — hold the vial between thumb and forefinger and rotate slowly until the powder dissolves completely. If it doesn't dissolve within 2–3 minutes of gentle swirling, let it sit in the refrigerator for 30 minutes and try again.
4. Improper storage after reconstitution. Reconstituted peptides must go in the refrigerator (36–46°F / 2–8°C) immediately. Leaving a reconstituted vial at room temperature — even for a few hours — accelerates degradation. Never freeze reconstituted peptides; ice crystal formation physically damages the dissolved peptide structure. Store vials upright to keep the solution away from the rubber stopper.
5. Cross-contamination between vials. Use a new syringe every time you draw from a vial. Never reuse a syringe that has touched your skin or another vial — this introduces bacteria into the sterile environment. If you're drawing from both a BAC water vial and a peptide vial, use the same fresh syringe for that single reconstitution, but discard it after. For daily dosing draws, always use a new syringe.

How Long Do Reconstituted Peptides Last?

Stability varies by peptide. Here are evidence-based timelines for common peptides stored correctly (refrigerated at 36–46°F, protected from light, stored upright):

Signs your reconstituted peptide has degraded:

• Cloudiness or turbidity — a clear solution turning hazy indicates protein aggregation or bacterial contamination
• Visible particulates — any floating particles, fibers, or sediment means discard immediately
• Color change — most peptide solutions are colorless; yellowing or darkening signals degradation
• Reduced efficacy — if your dose stops producing the expected effects partway through a vial, degradation is the likely cause
• Unusual smell — BAC water has a faint alcohol scent; anything else is contamination

Pro tip: If you won't finish a vial within 3 weeks, consider reconstituting with less BAC water (e.g., 1 mL instead of 2 mL) so each draw contains a higher concentration — meaning fewer total draws and faster vial depletion.

Reconstitution Calculator

The single most important formula for peptide users. Once you understand this, you can reconstitute any peptide at any concentration.

The formula:

Desired dose (mcg) ÷ Concentration (mcg/mL) = Injection volume (mL)

And since 1 mL = 100 units on a U-100 insulin syringe:

Injection volume (mL) × 100 = Units to draw on syringe

Step 1: Calculate your concentration

Total peptide in vial (mcg) ÷ BAC water added (mL) = Concentration (mcg/mL)

Worked Example 1: BPC-157 250 mcg dose

• Vial: 5 mg (5,000 mcg) BPC-157
• BAC water added: 2 mL
• Concentration: 5,000 ÷ 2 = 2,500 mcg/mL
• Desired dose: 250 mcg
• Injection volume: 250 ÷ 2,500 = 0.1 mL
• Syringe units: 0.1 × 100 = 10 units on insulin syringe

Worked Example 2: Ipamorelin 200 mcg dose (from an Ipamorelin + CJC-1295 stack)

• Vial: 2 mg (2,000 mcg) Ipamorelin
• BAC water added: 2 mL
• Concentration: 2,000 ÷ 2 = 1,000 mcg/mL
• Desired dose: 200 mcg
• Injection volume: 200 ÷ 1,000 = 0.2 mL
• Syringe units: 0.2 × 100 = 20 units on insulin syringe

Worked Example 3: PT-141 (Bremelanotide) 1.75 mg dose

• Vial: 10 mg (10,000 mcg) PT-141
• BAC water added: 2 mL
• Concentration: 10,000 ÷ 2 = 5,000 mcg/mL
• Desired dose: 1,750 mcg (1.75 mg)
• Injection volume: 1,750 ÷ 5,000 = 0.35 mL
• Syringe units: 0.35 × 100 = 35 units on insulin syringe

Quick reference — common concentrations:

Bookmark this page and come back whenever you reconstitute a new peptide. The math takes 10 seconds once you've done it a few times.