The Peptide Reconstitution Calculator
Select your syringe size, vial quantity, and desired dose — get the exact unit mark to draw to every time. Zero math required.
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How to Use This Calculator
This tool calculates the precise draw volume — expressed in insulin syringe units — needed to achieve your target peptide dose after reconstituting a lyophilized vial. Select your syringe size, vial mass, volume of bacteriostatic water added, and desired dose per injection. The result tells you exactly where to pull the plunger to.
Correct Peptide Reconstitution
Peptides are typically delivered as lyophilized (freeze-dried) powder — a form that is stable to short-term temperature fluctuations during shipping and handling. At room temperature, lyophilized peptides remain stable for several weeks. For long-term storage, keep them at −20°C.
Before use, the lyophilized powder must be reconstituted by dissolving it in an appropriate solvent to form a clear solution. Accurate reconstitution is essential to ensure the peptide retains full potency and bioactivity.
Prepare Your Environment
Absolute sterility is required. Before reconstituting, ensure you have all necessary materials ready:
- Lyophilized peptide vial
- Bacteriostatic water — the preferred reconstitution solvent for most peptides
- Sterile insulin syringes — appropriate volume for your dosing protocol
- Sterile gloves and alcohol prep swabs
Wash hands thoroughly, wear clean gloves, and wipe all vial septa with an alcohol swab before inserting any needle.
Adding the Solvent
Using a sterile syringe, draw the required volume of bacteriostatic water and inject it slowly into the peptide vial. Tilt the vial at a 45° angle and direct the stream along the inner glass wall — this prevents foam formation and promotes even dissolution of the lyophilized cake. Do not shake vigorously; gently swirl if needed until the solution is fully clear.
Storage of Reconstituted Peptides
Once reconstituted, peptide solutions should be stored at +4°C (refrigerator) and used within 3–4 weeks. For longer-term storage, aliquot and freeze at −20°C, where solutions typically remain stable for 3–4 months. Avoid repeated freeze-thaw cycles, as each cycle can cause progressive peptide degradation.
Frequently Asked Questions
How do I reconstitute a peptide?
Draw the required volume of bacteriostatic water into a sterile syringe, then slowly inject it along the inner wall of the peptide vial. Gently swirl — never shake — until the powder fully dissolves into a clear solution. Use this calculator to determine exactly how much BAC water to add based on your desired concentration.
How much BAC water do I add to a 5mg peptide vial?
The amount depends on your desired concentration. Adding 1 mL to a 5 mg vial gives 5,000 mcg/mL; adding 2 mL gives 2,500 mcg/mL. Most researchers use 1–2 mL for a 5 mg vial. Enter your chosen volume into ThePepCalc to get the exact syringe units per dose.
What is the formula for peptide reconstitution?
The math behind this calculator uses three simple steps:
Step 1 — Find your concentration:
Concentration (mg/mL) = Total Peptide (mg) ÷ BAC Water (mL)
Step 2 — Find your injection volume:
Injection Volume (mL) = Desired Dose (mg) ÷ Concentration (mg/mL)
Step 3 — Convert to syringe units:
Syringe Units = Injection Volume (mL) × 100
Example: A 5mg vial with 2mL of BAC water gives a concentration of 2.5mg/mL. For a 500mcg (0.5mg) dose, divide 0.5 by 2.5 to get 0.2mL, which equals 20 units on a U-100 insulin syringe.
How many units do I draw for a 250mcg dose?
It depends on your concentration. If you reconstituted a 5 mg vial with 2 mL BAC water (2,500 mcg/mL), a 250 mcg dose equals 0.1 mL, which is 10 units on a 100-unit syringe. Use the calculator above to get the exact mark for your specific vial and syringe combination.
How long does a reconstituted peptide last?
When reconstituted with bacteriostatic water and stored at +4°C (refrigerator), most peptides remain stable for 3–4 weeks. For longer storage, aliquot into individual doses and freeze at −20°C, where stability extends to 3–4 months. Avoid repeated freeze-thaw cycles as each cycle can degrade peptide potency.
What syringe do I use for peptide injections?
Insulin syringes are standard for peptide research. The most common sizes are 0.3 mL (30 units), 0.5 mL (50 units), and 1 mL (100 units). A 1 mL / 100-unit syringe is the most versatile and works with ThePepCalc's full range of doses and concentrations.
Can I use sterile water instead of BAC water?
Sterile water can dissolve peptides but offers no bacteriostatic protection, meaning the reconstituted solution should be used within 24 hours. Bacteriostatic water (BAC water) with 0.9% benzyl alcohol is strongly preferred as it inhibits bacterial growth and extends shelf life to 3–4 weeks when refrigerated.
How do I reconstitute BPC-157?
BPC-157 typically comes as a 5 mg or 10 mg lyophilized vial. Add 1–2 mL of bacteriostatic water slowly along the vial wall and gently swirl until the solution is fully clear. Store at +4°C and use within 3–4 weeks. Use ThePepCalc to calculate the exact syringe units for your BPC-157 dose and syringe size.
Research-grade peptides available at bqsciences.com