Dosing Preparation Guide
Overview
Calculating the correct draw volume is the mathematical heart of every peptide research protocol. Errors in concentration math silently corrupt experiments — an off-by-one-decimal error in concentration produces a 10× dosing mistake that no amount of careful sterile technique can correct. This guide walks through the complete calculation chain: from raw unit conversions through concentration formula to final draw volume, with five fully worked examples and a common errors table.
Use the Calculator. The Alpha Tides Peptide Calculator automates all calculations in this guide. Input your vial size, BAC water volume, and target dose — the calculator outputs exact draw volumes in both µL and U-100 insulin syringe units. Manual calculation knowledge is essential for verification and troubleshooting, but the calculator eliminates arithmetic errors in routine use.
This guide assumes you are using U-100 insulin syringes as your measurement instrument. If you are using a different syringe type, see the Syringe Selection Guide for scale conversion factors before proceeding.
Unit Conversions
Peptide dosing involves three measurement systems that must be kept distinct: mass units (µg, mg), volume units (µL, mL), and concentration units (mass/volume). Conversion errors between these systems are the most common source of dosing mistakes.
Mass Unit Conversions
| From | To | Conversion | Example |
|---|---|---|---|
| milligrams (mg) | micrograms (µg / mcg) | × 1,000 | 5 mg = 5,000 µg |
| micrograms (µg) | milligrams (mg) | ÷ 1,000 | 500 µg = 0.5 mg |
| micrograms (µg) | nanograms (ng) | × 1,000 | 1 µg = 1,000 ng |
Volume Unit Conversions
| From | To | Conversion | Example |
|---|---|---|---|
| milliliters (mL) | microliters (µL) | × 1,000 | 0.5 mL = 500 µL |
| microliters (µL) | milliliters (mL) | ÷ 1,000 | 250 µL = 0.25 mL |
| U-100 syringe units | microliters (µL) | × 10 | 20 units = 200 µL |
| microliters (µL) | U-100 syringe units | ÷ 10 | 150 µL = 15 units |
IU Conversions (Compound-Specific)
Some peptides — particularly growth hormone secretagogues and certain hormones — are dosed in International Units (IU) rather than mass units. IU-to-mass conversions are compound-specific and cannot be generalized. Common examples:
- Recombinant human growth hormone (rhGH): 1 mg ≈ 3 IU (WHO 1st International Standard)
- Insulin: 1 IU = 34.7 µg (human insulin)
- Most synthetic research peptides: Dosed in mass units (µg or mg) — IU conversions do not apply
Always verify the specific compound's dosing convention before calculating. The compound profiles in the Research Compounds section specify which unit system applies to each compound.
Concentration Math
Concentration is the mass of peptide dissolved per unit volume of solution. After reconstitution, concentration is fixed by the vial size and the volume of BAC water you added. You cannot change the concentration of a reconstituted vial without discarding it and starting again.
Concentration Formula
Concentration (mg/mL) = Peptide mass (mg) ÷ BAC water volume (mL)
Reconstitution Concentration Examples
| Vial Size | BAC Water Added | Final Concentration | Concentration in µg/mL |
|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 5,000 µg/mL |
| 5 mg | 2 mL | 2.5 mg/mL | 2,500 µg/mL |
| 5 mg | 5 mL | 1 mg/mL | 1,000 µg/mL |
| 2 mg | 2 mL | 1 mg/mL | 1,000 µg/mL |
| 10 mg | 5 mL | 2 mg/mL | 2,000 µg/mL |
| 500 µg (0.5 mg) | 1 mL | 0.5 mg/mL | 500 µg/mL |
Choose Concentrations That Yield Round Numbers. When selecting how much BAC water to add during reconstitution, choose a volume that produces a concentration where your target dose corresponds to a round number of µL or U-100 units. For example: a 5 mg vial reconstituted with 5 mL yields 1 mg/mL — at this concentration, a 1 mg dose = 1 mL = 100 units, and a 250 µg dose = 0.25 mL = 25 units. These are easy to read accurately on a syringe. Avoid concentrations that force you to draw to a fractional unit mark.
Draw Volume Formula
Once concentration is known, draw volume is calculated using a straightforward formula.
The Formula
Draw Volume (µL) = [Desired dose (µg) ÷ Concentration (µg/mL)] × 1,000
Or equivalently:
Draw Volume (mL) = Desired dose (mg) ÷ Concentration (mg/mL)
Converting Draw Volume to Syringe Units (U-100)
After calculating the draw volume in µL, convert to U-100 syringe units by dividing by 10:
U-100 Units = Draw Volume (µL) ÷ 10
Worked Example Scenarios
The following five scenarios cover common research configurations. In each case, the math is shown step by step.
Example 1: BPC-157 — Standard Reconstitution
- Vial: 5 mg BPC-157
- BAC water added: 2.5 mL
- Target dose: 250 µg
Step 1 — Concentration: 5 mg ÷ 2.5 mL = 2 mg/mL (2,000 µg/mL)
Step 2 — Draw volume: 250 µg ÷ 2,000 µg/mL × 1,000 = 125 µL
Step 3 — Syringe units: 125 µL ÷ 10 = 12.5 U-100 units
Draw to the 12.5 unit mark on a U-100 syringe (between the 12 and 13 unit lines).
Example 2: TB-500 — Lower Concentration
- Vial: 5 mg TB-500
- BAC water added: 5 mL
- Target dose: 500 µg
Step 1 — Concentration: 5 mg ÷ 5 mL = 1 mg/mL (1,000 µg/mL)
Step 2 — Draw volume: 500 µg ÷ 1,000 µg/mL × 1,000 = 500 µL
Step 3 — Syringe units: 500 µL ÷ 10 = 50 U-100 units
Draw to the 50 unit mark on a U-100 syringe. This is exactly the midpoint of a 1 mL syringe.
Example 3: Ipamorelin — Small Vial, Precise Dosing
- Vial: 2 mg Ipamorelin
- BAC water added: 2 mL
- Target dose: 100 µg
Step 1 — Concentration: 2 mg ÷ 2 mL = 1 mg/mL (1,000 µg/mL)
Step 2 — Draw volume: 100 µg ÷ 1,000 µg/mL × 1,000 = 100 µL
Step 3 — Syringe units: 100 µL ÷ 10 = 10 U-100 units
Draw to the 10 unit mark. Simple and easy to read accurately.
Example 4: CJC-1295 — Higher Concentration Vial
- Vial: 5 mg CJC-1295
- BAC water added: 1 mL
- Target dose: 1 mg (1,000 µg)
Step 1 — Concentration: 5 mg ÷ 1 mL = 5 mg/mL (5,000 µg/mL)
Step 2 — Draw volume: 1,000 µg ÷ 5,000 µg/mL × 1,000 = 200 µL
Step 3 — Syringe units: 200 µL ÷ 10 = 20 U-100 units
Draw to the 20 unit mark. Note: at 5 mg/mL concentration, each syringe unit = 50 µg — read carefully.
Example 5: Hexarelin — Fractional µg Dosing
- Vial: 2 mg Hexarelin
- BAC water added: 2 mL
- Target dose: 50 µg
Step 1 — Concentration: 2 mg ÷ 2 mL = 1 mg/mL (1,000 µg/mL)
Step 2 — Draw volume: 50 µg ÷ 1,000 µg/mL × 1,000 = 50 µL
Step 3 — Syringe units: 50 µL ÷ 10 = 5 U-100 units
Draw to the 5 unit mark. This is a small volume — use a 0.3 mL (30-unit) syringe for better resolution at this scale. Consider increasing BAC water to 4 mL (giving 0.5 mg/mL) if you need even finer resolution.
Common Dosing Errors
The following table catalogs the most frequent calculation mistakes observed in peptide research and how to avoid them.
| Error | Example of Mistake | Effect on Dose | Prevention |
|---|---|---|---|
| Wrong unit: treating µg as mg | Calculating dose of "500" meaning mg when the compound is dosed in µg — results in target dose 1,000× too high | 1,000× overdose in calculation (syringe may not hold it, but math is corrupted) | Always specify units explicitly: "500 µg" not "500" |
| Confusing U-100 with U-40 syringe | Drawing "10 units" on a U-40 syringe when U-100 calculation was used | 2.5× overdose (U-40 gives 250 µL where U-100 gives 100 µL) | Confirm syringe type from packaging before every use; use U-100 exclusively for peptide research |
| Forgetting to convert mg to µg in draw formula | Dose = 0.5 (mg), concentration = 1,000 (µg/mL) — divides as 0.5 ÷ 1,000 = very small number | 1,000× underdose in calculation | Convert all values to the same unit before calculating; use µg and µg/mL throughout |
| Not accounting for dead volume (luer-lock syringes) | Calculating 100 µL dose but 10 µL remains in syringe hub — delivers 90 µL | Up to 10% underdose per injection | Use integrated-needle syringes (dead volume <3 µL); or draw 10% more to compensate |
| Decimal point error in concentration | Recording 1 mg/mL as 10 mg/mL on vial label — subsequent calculations 10× off | 10× under- or overdose depending on direction | Double-check label immediately after writing; have second researcher verify |
| Drawing from wrong vial after mixing session | Two vials on the bench — drawing from Compound A when intending to draw Compound B | Wrong compound entirely | Keep only one vial on the bench at a time; return all others to storage before proceeding |
Verify Before You Draw. Before drawing any volume, verbally confirm (or write down and check): compound name, vial concentration, target dose, and calculated draw volume. This two-second check catches the majority of errors before they happen. Use the Alpha Tides Peptide Calculator as an independent cross-check on manual calculations.
References
- Shargel L, Wu-Pong S, Yu ABC. Applied Biopharmaceutics and Pharmacokinetics. 6th ed. New York: McGraw-Hill Medical; 2012. ISBN: 9780071603935.
- Ansel HC, Stoklosa MJ. Pharmaceutical Calculations. 11th ed. Philadelphia: Lippincott Williams & Wilkins; 2001.
- Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. "Stability of protein pharmaceuticals: an update." Pharm Res. 2010;27(4):544–575. PMID: 20143256. PubMed →
- United States Pharmacopeia. "USP <1> Injections and Implanted Drug Products — Product Quality Tests." USP-NF, 2023.
- World Health Organization. "International Standard for Somatropin (Human Growth Hormone)." WHO Technical Report Series, 2nd International Standard, 1994.