Last updated: May 18, 2026
The basic formula
To calculate the volume to draw for any peptide dose:
Volume to draw (mL) = Target dose (mcg) / Concentration (mcg/mL)
Concentration (mcg/mL) = (mg per vial × 1000) / mL of BAC water added
Worked examples
Example 1: 5mg Ipamorelin vial, 2mL BAC, target 300 mcg dose
- Concentration: (5 × 1000) / 2 = 2,500 mcg/mL
- Volume per 300 mcg: 300 / 2500 = 0.12 mL
- On insulin syringe: 0.12 mL × 100 = 12 units
Example 2: 10mg BPC-157 vial, 5mL BAC, target 250 mcg dose
- Concentration: (10 × 1000) / 5 = 2,000 mcg/mL
- Volume per 250 mcg: 250 / 2000 = 0.125 mL
- On insulin syringe: 12.5 units
Example 3: 5mg Sermorelin vial, 1mL BAC, target 100 mcg dose
- Concentration: (5 × 1000) / 1 = 5,000 mcg/mL
- Volume per 100 mcg: 100 / 5000 = 0.02 mL
- On insulin syringe: 2 units
Use our free calculator
Enter the three values into our free peptide calculator for instant calculation in both mL and insulin syringe units.
Common mistakes
- Confusing mg and mcg: 1 mg = 1,000 mcg. Always work in mcg for peptide doses.
- Wrong vial size: Verify the vial label vs what was ordered. 5mg and 10mg vials need different math.
- Insulin syringe units: A 1mL syringe has 100 units. A 0.5mL syringe has 50 units. Different syringes have different scales.
- Drawing air: Tap the syringe to remove air bubbles before pushing the plunger back to the correct unit mark.
Choosing your BAC water volume
More BAC water = more dilute = more volume per dose = easier to measure small doses accurately. For research dosing, 2-3 mL BAC per 5mg vial provides reasonable concentration. For very small doses (like 50 mcg of IGF-1), use 5-10 mL BAC to dilute enough for accurate measurement on a 1mL syringe.
How accurate are insulin syringes?<br />
A 1mL insulin syringe is marked in 1-unit increments (0.01 mL). For research dosing, drawing to ±1 unit is sufficient precision for most peptides.
Can I use a regular syringe?<br />
Yes, but insulin syringes (smaller needle, finer markings) are preferred for subcutaneous peptide injection.
What if my math gives a fractional unit?<br />
Round to the nearest unit. A dose calculated as 12.4 units can be drawn as 12 units; this is well within the precision required for peptide dosing.
How much BAC water should I use?<br />
Generally 1-3 mL per 5mg vial. More water means more diluted product, requiring more volume per dose — useful for very small doses but reduces shelf life since you have more volume.