Peptide reconstitution requires 3 values: the vial amount in milligrams, the volume of bacteriostatic water added, and the desired dose in micrograms. This calculator converts those inputs into the exact syringe units to draw on a U-100 insulin syringe - eliminating the manual math that causes dosing errors. It covers 65+ peptides including semaglutide, tirzepatide, BPC-157, ipamorelin, and retatrutide with preset vial sizes and common dose values. Every peptide links directly to its independent lab test data on Peptigrity, so you can verify purity before reconstituting. Not sure how much BAC water to add? Use the BAC water calculator first. To compare costs across vendors after reconstitution, see the cost-per-dose calculator.
The calculator performs 3 operations in sequence. First, it determines concentration by dividing the vial's total peptide content (converted to micrograms) by the bacteriostatic water volume in milliliters. A 5 mg vial reconstituted with 2 mL of water produces a concentration of 2,500 mcg/mL. Second, it calculates the dose volume by dividing your target dose by that concentration - a 250 mcg dose from a 2,500 mcg/mL solution requires 0.1 mL. Third, it converts the volume to syringe units by multiplying by 100, yielding 10 units on a standard U-100 insulin syringe.
The visual syringe updates in real time as you adjust inputs. It fills to the exact mark you need to draw and turns red with a warning when your dose volume exceeds the syringe's capacity - a signal to add more bacteriostatic water, reduce your dose, or switch to a larger syringe.
Three unit conversions cause the majority of peptide dosing errors - milligrams to micrograms, millilitres to syringe units, and the distinction between syringe units and International Units.
Milligrams to micrograms: 1 mg = 1,000 mcg. A 5 mg vial contains 5,000 mcg. A dose of 250 mcg is 0.25 mg. Confusing mg and mcg produces a 1,000× error - the single most common dosing mistake. This calculator accepts both units via the dose input buttons and converts automatically, but always verify which unit you're working in before drawing.
Millilitres to syringe units: On a U-100 insulin syringe, 100 units = 1 mL. Therefore 10 units = 0.1 mL, and 1 unit = 0.01 mL. This relationship is fixed regardless of the peptide or concentration. Syringe capacity differs by size - a 30-unit syringe holds 0.3 mL, a 50-unit holds 0.5 mL, and a 100-unit holds 1.0 mL - but all three use the same 100-units-per-mL scale.
IU (International Units) vs syringe units: IU measures biological activity and is used for compounds such as HGH and insulin. It is not interchangeable with insulin syringe units. A "10 unit" draw on a syringe is a volume measurement (0.1 mL), not an IU measurement. This calculator uses weight-based dosing (mcg/mg), which is the standard for the 65 peptides tracked on Peptigrity. For a detailed walkthrough of the dosing math with worked examples, see the how to calculate peptide doses guide.
The volume of bacteriostatic water you add does not change the total peptide - a 5 mg vial contains 5 mg regardless of dilution. What changes is the concentration, which determines how many syringe units you draw per dose. The table below lists commonly used BAC water volumes for popular peptides at typical doses.
| Peptide | Vial Size | Typical Dose | Common BAC Water | Concentration | Draw per Dose |
|---|---|---|---|---|---|
| BPC-157 | 5 mg | 250 mcg | 2 mL | 2.5 mg/mL | 10 units |
| BPC-157 | 10 mg | 500 mcg | 2 mL | 5.0 mg/mL | 10 units |
| TB-500 | 5 mg | 2.5 mg | 1 mL | 5.0 mg/mL | 50 units |
| Ipamorelin | 5 mg | 200 mcg | 2 mL | 2.5 mg/mL | 8 units |
| CJC-1295 no DAC | 5 mg | 100 mcg | 2 mL | 2.5 mg/mL | 4 units |
| Semaglutide | 3 mg | 250 mcg | 1 mL | 3.0 mg/mL | 8 units |
| Semaglutide | 5 mg | 1 mg | 1 mL | 5.0 mg/mL | 20 units |
| Tirzepatide | 10 mg | 2.5 mg | 2 mL | 5.0 mg/mL | 50 units |
| Tirzepatide | 30 mg | 5 mg | 3 mL | 10.0 mg/mL | 50 units |
| Retatrutide | 12 mg | 2 mg | 2 mL | 6.0 mg/mL | 33 units |
| Sermorelin | 5 mg | 200 mcg | 2 mL | 2.5 mg/mL | 8 units |
| GHK-Cu | 50 mg | 1 mg | 5 mL | 10.0 mg/mL | 10 units |
| Selank | 5 mg | 250 mcg | 2 mL | 2.5 mg/mL | 10 units |
| Semax | 5 mg | 200 mcg | 2 mL | 2.5 mg/mL | 8 units |
| PT-141 | 10 mg | 1 mg | 2 mL | 5.0 mg/mL | 20 units |
| Melanotan II | 10 mg | 500 mcg | 2 mL | 5.0 mg/mL | 10 units |
| MOTS-C | 5 mg | 5 mg (weekly) | 1 mL | 5.0 mg/mL | 100 units |
| Epithalon | 10 mg | 5 mg | 2 mL | 5.0 mg/mL | 100 units |
These are starting points. Use the calculator above with your specific vial and dose for exact numbers. If your calculated draw falls under 5 units, add more BAC water to dilute the solution - the BAC water calculator recommends volumes based on your dose and syringe type. For a full guide to the physical mixing process, see the step-by-step reconstitution guide.
Most peptides dissolve in bacteriostatic water within 1-3 minutes of gentle swirling. A few compounds behave differently:
| Peptide | Note |
|---|---|
| GHK-Cu | Solution may show a faint blue tint - this is normal and results from the copper ion. Clear blue is fine. Cloudy or dark = discard. |
| Melanotan II | Hydrophobic peptide. May take 5-10 minutes to dissolve fully. Do not shake - set the vial down and let it sit, then swirl gently. |
| PT-141 | Same hydrophobic behavior as Melanotan II. Allow extra dissolution time. |
| Semaglutide | Use 0.5-1 mL BAC water for higher concentration. Doses are small (250-2,500 mcg/week) and benefit from precise, low-volume draws. |
| TB-500 | Doses are larger (2-5 mg). Draw volumes will be high - a 100-unit syringe is recommended. |
| NAD+ | Naturally acidic. Use saline BAC water (bacteriostatic sodium chloride 0.9%) to buffer pH and reduce injection site burning. Standard BAC water works but may cause significant discomfort. |
| MOTS-C | Typical weekly dose (5 mg) uses the entire vial at most concentrations. Plan reconstitution accordingly - a smaller BAC water volume (1 mL) keeps the draw to a single syringe. |
For compound-specific dosing protocols, dose ranges, and evidence levels, see the individual peptide guide pages.
The calculator handles the math - but these errors happen before or after the numbers.
1. Spraying BAC water directly onto the powder. Direct impact from the syringe needle can denature the peptide. Aim at the inside wall of the vial so water trickles down the glass and pools at the bottom, gradually dissolving the powder.
2. Shaking the vial. Shaking creates micro-bubbles and shear forces that break peptide bonds. Swirl gently or roll the vial between your palms. If foam forms, set the vial down for 15-30 minutes - it will dissipate.
3. Using sterile water for a multi-dose vial. Sterile water for injection contains no preservative. After the first needle puncture, bacteria can colonize the solution within hours. Bacteriostatic water (0.9% benzyl alcohol) provides antimicrobial protection for up to 28 days of repeated draws.
4. Forgetting to label the vial. Without a label, you lose track of the compound, reconstitution date, and concentration - making accurate dosing impossible after the first draw. Write: compound name, date reconstituted, concentration (mg/mL), and discard date (28 days).
5. Storing at the wrong temperature. Reconstituted peptides require 2-8°C (standard refrigerator). Room temperature accelerates degradation. Freezing reconstituted solution can damage some peptides through ice crystal formation. Lyophilized (unreconstituted) powder should be stored at -20°C for long-term storage. For the full storage guide, see how to store peptides.
| Tool | What It Does |
|---|---|
| BAC Water Calculator | Determine how much bacteriostatic water to add based on your dose and syringe type |
| Cost-per-Dose Calculator | Convert vial prices into cost per dose, per day, per week, and per month |
| Purity Comparison Tool | Compare independent lab-tested HPLC purity across brands for any peptide |
| Blend Calculator | Multi-peptide vial dosing for GLOW, CJC/Ipa, BPC-157/TB-500, and custom blends |
| Reverse Calculator | Convert syringe units to mg/mcg, find BAC water volume for a target concentration, verify draws |
For compound-specific calculators with pre-loaded defaults, titration schedules, and dosing protocols:
| Compound | Calculator | Why Use It |
|---|---|---|
| Tirzepatide | Tirzepatide Calculator | 6-tier titration table, vial size guide (5-60 mg), syringe capacity warnings |
| Semaglutide | Semaglutide Calculator | 5-tier dose escalation, unit conversion reference, B12 compound guidance |
| Retatrutide | Retatrutide Calculator | Phase 2/3 titration protocol, triple-agonist dosing reference |
| BPC-157 | BPC-157 Calculator | Dosing by injury type, oral vs injection, Wolverine stack reference |
| GHK-Cu | GHK-Cu Calculator | Injection dosing by goal (skin, hair, healing) for 50-100 mg vials |
| MOTS-C | MOTS-C Calculator | Bolus, intermittent, and low-dose daily protocols |
| Tesamorelin | Tesamorelin Calculator | FDA-approved 2 mg protocol, visceral fat dosing, GHRH comparison |
| CJC-1295 + Ipamorelin | CJC/Ipa Calculator | GH secretagogue blend dosing, cycling, DAC vs no-DAC |
| BPC-157 + TB-500 | Wolverine Calculator | Wolverine stack blend dosing, loading vs maintenance, standalone TB-500 |
| Guide | What It Covers |
|---|---|
| How to Reconstitute Peptides Step by Step | The 7-step physical process - workspace prep through storage |
| How to Calculate Peptide Doses | The dosing formula explained with 4 worked examples and 7 common mistakes |
| How to Store Peptides | Temperature, shelf life, degradation signs, and lyophilized vs reconstituted storage |
| Subcutaneous vs Intramuscular Injection | Injection technique, site selection, and needle gauge |
| Peptide Stacking Guide | How to combine multiple peptides in a protocol |
Divide the vial amount (in mg) by the bacteriostatic water volume (in mL), then multiply by 1,000 to get concentration in mcg/mL. Divide your desired dose in mcg by that concentration to get the volume in mL. Multiply the volume by 100 for U-100 syringe units. Example: a 5 mg vial + 2 mL water = 2,500 mcg/mL. A 250 mcg dose requires 0.1 mL = 10 units. For a complete walkthrough with 4 compound-specific worked examples, see the how to calculate peptide doses guide.
The volume depends on the vial size and desired dose precision. More water produces a lower concentration, making small doses easier to measure accurately on a syringe. Common ranges: 1-2 mL for 2-5 mg vials, 2-3 mL for 10 mg vials, and 3-5 mL for 15 mg+ vials. The calculator adjusts concentration automatically when you change the water volume. The BAC water calculator recommends a specific volume based on your dose and syringe type.
Micrograms (mcg) and milligrams (mg) measure weight - 1 mg = 1,000 mcg. International Units (IU) measure biological activity and do not convert directly to weight without a compound-specific factor. Most research peptides such as BPC-157, semaglutide, and ipamorelin are dosed in mcg or mg. HGH and insulin use IU. This calculator uses weight-based dosing (mcg/mg), which is standard for 65 peptides tracked on Peptigrity.
Divide the total vial content (in mcg) by your dose size. A 10 mg vial (10,000 mcg) dosed at 250 mcg yields 40 doses. A 5 mg vial at the same dose yields 20. The calculator displays this automatically as "Doses per vial" - and the protocol planner extends it to show how many vials you need for a multi-week protocol.
Reconstituted peptides stored at 2-8°C (standard refrigerator) remain stable for approximately 3-4 weeks. Frozen aliquots at -20°C extend viability to 3-4 months. Avoid repeated freeze-thaw cycles, which degrade peptide integrity. Bacteriostatic water (containing 0.9% benzyl alcohol) inhibits microbial growth better than sterile water, making it the preferred solvent for multi-dose vials. For reconstitution best practices, see the step-by-step reconstitution guide. For storage temperature and shelf life details, see how to store peptides.
Sterile water works for single-use reconstitution but lacks the 0.9% benzyl alcohol preservative that bacteriostatic water contains. Without it, microbial contamination risk increases with each needle insertion. Use sterile water only when the entire vial will be used in one session. For multi-dose vials drawn over days or weeks, bacteriostatic water is required.
U-100 insulin syringes in 0.3 mL (30 unit), 0.5 mL (50 unit), or 1.0 mL (100 unit) sizes are standard for subcutaneous peptide administration. Smaller syringes provide finer graduation marks, improving accuracy for small doses. If your calculated dose is under 10 units, a 0.3 mL syringe offers the best precision. The calculator flags when your dose volume exceeds the selected syringe's capacity. For injection technique and site selection, see the subcutaneous vs intramuscular injection guide.
Request the vendor's Certificate of Analysis (CoA) showing HPLC purity and mass spectrometry identity confirmation. Then cross-reference against independent test data - Peptigrity aggregates 6168+ community-submitted lab tests across 231+ shops tested by labs listed in the testing labs directory. A vendor with 10+ independent tests averaging 99%+ purity is a strong quality signal. Learn more in how to verify peptide quality before you buy.
This calculator is for educational and research purposes only and does not constitute medical advice. Peptides discussed may be investigational compounds not approved by the FDA for human use. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.