Peptide Reconstitution Math: Step-by-Step Calculation Guide with Worked Examples
Comprehensive guide to peptide reconstitution mathematics — unit conversions (mg to mcg), concentration calculations (mg/mL), dose volume calculations, and 10 worked examples covering common research peptides with different vial sizes and target doses.
TL;DR
- Core formula: Dose volume (mL) = Desired dose (mg) ÷ Concentration (mg/mL)
- Convert mcg to mg before calculating: 500mcg = 0.5mg
- Insulin syringe units: multiply mL × 100 to get the unit marking to draw to
- More BAC water added = lower concentration = larger, easier-to-measure dose volumes
Disclaimer: For educational and research purposes only — not medical advice.
Accurate peptide reconstitution and dose calculation is a fundamental skill for research. Errors in reconstitution math directly translate to under- or over-dosing — undermining research validity. This guide provides the mathematical framework with fully worked examples for 10 common research scenarios.
The Three Essential Formulas
Formula 1: Concentration
Concentration (mg/mL) = Amount of peptide in vial (mg) ÷ Volume of BAC water added (mL)
Formula 2: Dose Volume
Dose volume (mL) = Desired dose (mg) ÷ Concentration (mg/mL)
Formula 3: Total Doses Per Vial
Number of doses = Total peptide in vial (mg) ÷ Dose per injection (mg)
Unit Conversion (memorize this)
- 1 mg = 1000 mcg
- To convert mcg → mg: divide by 1000
- To convert mg → mcg: multiply by 1000
Reading Insulin Syringes
Insulin syringes are marked in "units" (U) assuming U-100 insulin (100 IU per mL):
- 1 unit = 0.01 mL
- 10 units = 0.1 mL
- 50 units = 0.5 mL
- 100 units = 1.0 mL
To find the syringe marking for any mL dose: Syringe marking (units) = mL dose × 100
Example: 0.2 mL → 0.2 × 100 = 20 units marking on the syringe
10 Worked Examples
Example 1: BPC-157 (5mg vial, 500mcg dose)
- Step 1: Add 2mL BAC water → Concentration = 5mg ÷ 2mL = 2.5mg/mL = 2500mcg/mL
- Step 2: Convert dose: 500mcg = 0.5mg
- Step 3: Volume = 0.5mg ÷ 2.5mg/mL = 0.2mL
- Syringe marking: 0.2 × 100 = 20 units
- Doses per vial: 5mg ÷ 0.5mg = 10 doses
Example 2: BPC-157 (5mg vial, 250mcg dose, more water for easier measurement)
- Step 1: Add 5mL BAC water → Concentration = 5mg ÷ 5mL = 1mg/mL = 1000mcg/mL
- Step 2: Convert dose: 250mcg = 0.25mg
- Step 3: Volume = 0.25mg ÷ 1mg/mL = 0.25mL
- Syringe marking: 0.25 × 100 = 25 units
- Doses per vial: 5mg ÷ 0.25mg = 20 doses
Example 3: TB-500 (5mg vial, 2.5mg dose)
- Step 1: Add 1mL BAC water → Concentration = 5mg ÷ 1mL = 5mg/mL
- Step 2: Volume = 2.5mg ÷ 5mg/mL = 0.5mL
- Syringe marking: 0.5 × 100 = 50 units
- Doses per vial: 5mg ÷ 2.5mg = 2 doses
Example 4: Ipamorelin (5mg vial, 200mcg dose)
- Step 1: Add 2mL BAC water → Concentration = 5mg ÷ 2mL = 2.5mg/mL = 2500mcg/mL
- Step 2: Convert: 200mcg = 0.2mg
- Step 3: Volume = 0.2mg ÷ 2.5mg/mL = 0.08mL
- Syringe marking: 0.08 × 100 = 8 units
- Doses per vial: 5000mcg ÷ 200mcg = 25 doses
Example 5: MOD GRF 1-29 (2mg vial, 100mcg dose)
- Step 1: Add 2mL BAC water → Concentration = 2mg ÷ 2mL = 1mg/mL = 1000mcg/mL
- Step 2: Convert: 100mcg = 0.1mg
- Step 3: Volume = 0.1mg ÷ 1mg/mL = 0.1mL
- Syringe marking: 0.1 × 100 = 10 units
- Doses per vial: 2000mcg ÷ 100mcg = 20 doses
Example 6: GHK-Cu (5mg vial, 1mg dose)
- Step 1: Add 5mL BAC water → Concentration = 5mg ÷ 5mL = 1mg/mL
- Step 2: Volume = 1mg ÷ 1mg/mL = 1.0mL
- Syringe marking: 1.0 × 100 = 100 units (full 1mL insulin syringe)
- Doses per vial: 5mg ÷ 1mg = 5 doses
Example 7: MOTS-c (5mg vial, 5mg weekly dose)
- Step 1: Add 1mL BAC water → Concentration = 5mg ÷ 1mL = 5mg/mL
- Step 2: Volume = 5mg ÷ 5mg/mL = 1.0mL
- Syringe marking: 1.0 × 100 = 100 units
- Doses per vial: 5mg ÷ 5mg = 1 dose (entire vial per week)
Example 8: SS-31 (5mg vial, 2mg dose)
- Step 1: Add 5mL BAC water → Concentration = 5mg ÷ 5mL = 1mg/mL
- Step 2: Volume = 2mg ÷ 1mg/mL = 2.0mL
- Note: Exceeds 1mL syringe capacity — use 3mL syringe or reconstitute in 2.5mL (2mg/mL): then 2mg ÷ 2mg/mL = 1.0mL
- Syringe marking: 1.0 × 100 = 100 units
Example 9: Semaglutide (3mg vial, 0.25mg starting dose)
- Step 1: Add 1.5mL BAC water → Concentration = 3mg ÷ 1.5mL = 2mg/mL
- Step 2: Volume = 0.25mg ÷ 2mg/mL = 0.125mL
- Syringe marking: 0.125 × 100 = 12.5 units (between 12 and 13 unit marks)
- Doses per vial: 3mg ÷ 0.25mg = 12 doses (at starting dose)
Example 10: Semax (10mg vial, intranasal spray, 500mcg per spray)
- Step 1: Add 10mL distilled water → Concentration = 10mg ÷ 10mL = 1mg/mL = 1000mcg/mL
- Step 2: Standard nasal spray pump delivers ~0.1mL per spray
- Step 3: 0.1mL × 1mg/mL = 0.1mg = 100mcg per spray
- For 500mcg dose: 5 sprays (500mcg total), distributed across both nostrils
- Doses per vial: 10,000mcg ÷ 500mcg = 20 doses (nasal, 5 sprays each)
Quick Reference Table
| Peptide | Vial | BAC Water | Concentration | Example Dose | Volume | Syringe |
|---|---|---|---|---|---|---|
| BPC-157 | 5mg | 2mL | 2.5mg/mL | 250mcg | 0.1mL | 10 units |
| TB-500 | 5mg | 1mL | 5mg/mL | 2.5mg | 0.5mL | 50 units |
| Ipamorelin | 5mg | 2mL | 2.5mg/mL | 200mcg | 0.08mL | 8 units |
| GHK-Cu | 5mg | 5mL | 1mg/mL | 1mg | 1.0mL | 100 units |
| Semaglutide | 3mg | 1.5mL | 2mg/mL | 0.25mg | 0.125mL | 12.5 units |
Use the Reconstitution Calculator → /calculators/reconstitution — enter vial size and desired dose for instant calculations
For educational and research purposes only. Not medical advice.
Disclaimer: For educational and research purposes only. Nothing in this article constitutes medical advice, diagnosis, or treatment recommendation. All compounds discussed are research chemicals or investigational compounds unless explicitly noted otherwise. Consult a qualified healthcare professional before making any health-related decisions. Researchers must comply with all applicable laws and regulations in their jurisdiction.
Written by the Peptide Performance Calculator Research Team
Our team compiles research guides based on published literature for educational purposes. All content is for research use only — not medical advice. Read our disclaimer.
Frequently Asked Questions
How do I calculate how much bacteriostatic water to add to a peptide vial?
The amount of water you add determines the concentration (how much peptide per mL). Choose a concentration that allows easy dose measurement. For example, a 5mg vial with 1mL water = 5mg/mL (5000mcg/mL); with 2mL = 2.5mg/mL; with 5mL = 1mg/mL. More water = lower concentration = larger injection volume per dose = easier accurate measurement with insulin syringes. Use the reconstitution calculator at /calculators/reconstitution for automatic calculations.
What is the difference between mg and mcg for peptide dosing?
1 milligram (mg) = 1000 micrograms (mcg). Most research peptide doses are in mcg (e.g., 250mcg BPC-157), while vials are sold in mg (e.g., 5mg vial). Converting: 250mcg = 0.25mg. A 5mg vial contains 5000mcg total. To find how many doses: 5000mcg ÷ 250mcg per dose = 20 doses per vial.
How do I read insulin syringe markings for peptide doses?
Insulin syringes are marked in 'units' (U) calibrated for U-100 insulin (100 IU/mL). Each unit marking = 0.01 mL. So 10 units = 0.1 mL, 50 units = 0.5 mL, 100 units = 1 mL. To use insulin syringes: calculate your dose in mL, then multiply by 100 to get the insulin syringe marking number. Example: 0.25 mL dose = 25 units on the insulin syringe.
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