Retatrutide Reconstitution Dose Calculator
Volume-per-dose tables across common vial sizes and target concentrations — tool-first, math explained step by step.
For research use only — not clinical guidance.
The Core Math: Three Steps
Every retatrutide reconstitution starts with one equation: concentration (mcg/mL) = total peptide mass (mcg) ÷ total liquid volume (mL). On a U-100 insulin syringe, each tick mark (1 unit) = 0.01 mL. That means 1 unit delivers 1/100th of whatever concentration you've created.
Step 1: Know your vial. Retatrutide is typically supplied in 5 mg, 10 mg, or 15 mg vials. Convert to micrograms: 5 mg = 5000 mcg; 10 mg = 10,000 mcg; 15 mg = 15,000 mcg.
Step 2: Choose your diluent volume. Common choices: 1 mL, 2 mL, or 3 mL of bacteriostatic water (0.9% benzyl alcohol preserved water, per USP <51> antimicrobial effectiveness testing). More diluent = lower concentration and larger injection volumes for the same dose — but easier handling.
Step 3: Calculate concentration and unit dose. For a 5 mg vial reconstituted with 2 mL: 5000 mcg ÷ 2 mL = 2500 mcg/mL. On a U-100 syringe, 1 unit = 0.01 mL × 2500 mcg/mL = 25 mcg per unit. So a 250 mcg dose requires 10 units.
Dose Tables for Common Vial Sizes
Below are volume-per-dose tables for the three most common retatrutide vial sizes. Each table assumes a specific diluent volume. The math is identical for any combination — just swap numbers.
5 mg Vial with 2 mL Diluent
Concentration: 2500 mcg/mL = 25 mcg per unit on U-100
| Target Dose (mcg) | Volume (mL) | U-100 Units | |------------------|-------------|-------------| | 50 | 0.02 | 2 | | 100 | 0.04 | 4 | | 250 | 0.10 | 10 | | 500 | 0.20 | 20 | | 1000 | 0.40 | 40 |
How to read this table: Find your target dose in the left column. The middle column shows the volume in mL. The right column shows the corresponding units on a U-100 syringe. At 2 mL diluent, a 250 mcg dose = 10 units — easy to read on any insulin syringe. For doses below 100 mcg (4 units), syringe accuracy becomes a concern. The smallest graduation on a standard U-100 syringe is 1 unit (0.01 mL). A 2-unit dose (50 mcg) = two tick marks — any parallax error or air bubble can shift the dose by 25% or more.
10 mg Vial with 2 mL Diluent
Concentration: 5000 mcg/mL = 50 mcg per unit on U-100
| Target Dose (mcg) | Volume (mL) | U-100 Units | |------------------|-------------|-------------| | 100 | 0.02 | 2 | | 250 | 0.05 | 5 | | 500 | 0.10 | 10 | | 1000 | 0.20 | 20 | | 2000 | 0.40 | 40 |
Watch out: A 100 mcg dose = only 2 units on this table. That's 0.02 mL — a tiny volume. The dead space in a standard insulin needle (typically 2-4 units, or 0.02-0.04 mL) can exceed the intended dose. Use low dead-space syringes (LDS) for doses under 5 units, or increase diluent volume to improve accuracy.
15 mg Vial with 3 mL Diluent
Concentration: 5000 mcg/mL = 50 mcg per unit on U-100
| Target Dose (mcg) | Volume (mL) | U-100 Units | |------------------|-------------|-------------| | 250 | 0.05 | 5 | | 500 | 0.10 | 10 | | 1000 | 0.20 | 20 | | 2000 | 0.40 | 40 | | 3000 | 0.60 | 60 |
Why 3 mL here? A 15 mg vial with only 1 mL diluent yields a concentration of 15,000 mcg/mL = 150 mcg per unit. A 250 mcg dose becomes 1.67 units — nearly impossible to measure accurately on a U-100 syringe. Using 3 mL drops the concentration to 5000 mcg/mL, making a 250 mcg dose a manageable 5 units.
Reconstitution Step-by-Step (Plain English)
What you need: Retatrutide vial, bacteriostatic water vial, 1 mL or 3 mL syringe with 18-20 gauge needle for diluent transfer, U-100 insulin syringe with 29-31 gauge needle for dosing, alcohol swabs.
Step 1: Clean. Wipe vial tops with alcohol swab. Let dry 10 seconds.
Step 2: Inject diluent. Draw up your chosen volume of bacteriostatic water into the transfer syringe. Inject it slowly down the side of the retatrutide vial — not directly onto the lyophilized powder. Direct jetting can cause foaming or denature the peptide.
Step 3: Swirl, don't shake. Gently swirl the vial until powder is fully dissolved. Shaking creates bubbles and can shear peptide chains. If foam forms, let it settle 5-10 minutes before drawing.
Step 4: Draw dose. Using the U-100 insulin syringe, draw air equal to your target volume. Inject air into the vial. Invert vial and draw the dose. Tap syringe to remove air bubbles. Confirm volume against the table above.
Step 5: Administer. For research use only — subcutaneous injection into loose skin of abdomen or thigh, per standard technique.
Why This Math Matters: Accuracy vs. Convenience
The trade-off between diluent volume and dose accuracy is the single most common error in peptide reconstitution. A 5 mg vial with 1 mL diluent gives 5000 mcg/mL = 50 mcg per unit. A 250 mcg dose = 5 units — easy. But a 50 mcg dose = 1 unit. At that volume, the dead space in a standard needle (2-4 units) means you're injecting 3-5 units worth of peptide even if you only draw 1 unit.
The fix: For low doses, use more diluent. A 5 mg vial with 2 mL gives 25 mcg per unit — a 50 mcg dose = 2 units. Still tight, but workable with careful technique and a low dead-space syringe. For doses under 100 mcg, consider using a 0.3 mL insulin syringe (30 units total volume, with 0.5-unit graduations) for finer control.
Real-world constraint: Bacteriostatic water vials are typically 30 mL. A 2 mL reconstitution uses about 7% of a vial. The remaining water stays sterile for 28 days per USP <797> guidelines for multi-dose vials — but only if you wipe the stopper with alcohol before each draw and store at room temperature (20-25°C).
Tool-First: The Retatrutide Reconstitution Calculator
Use the interactive calculator below to generate your own dose table. Enter your vial mass (mg), diluent volume (mL), and target dose (mcg). The tool outputs concentration (mcg/mL), volume per dose (mL), and U-100 units.
[Interactive calculator widget placeholder — embed here]
How to use the calculator:
- Enter your vial size (e.g., 5, 10, or 15 mg).
- Enter your diluent volume (e.g., 1, 2, or 3 mL).
- Enter your target dose in micrograms (e.g., 250).
- Read the result: volume in mL and U-100 units.
The math is the same as the tables above. The calculator just saves you from doing it by hand.
Where to Source Bacteriostatic Water
Bacteriostatic water (0.9% benzyl alcohol preserved water) is available from several online retailers. Look for USP-grade product with a 28-day multi-dose vial label. Common sources include:
- BAC Water Depot — USP-grade bacteriostatic water, 30 mL vials, sterile and preservative-tested.
- Peptide Sciences — Offers bacteriostatic water alongside research peptides, with COA available.
- Limitless Life — Carries 30 mL and 10 mL vials of bacteriostatic water, sterile filtered.
Storage note: Once opened, bacteriostatic water vials should be used within 28 days if stored at room temperature (20-25°C) and wiped with alcohol before each draw. Discard if cloudy or if any visible particles appear.
Disclaimer
This article is for research use only — not clinical guidance. The tables, calculator, and reconstitution steps are provided for informational purposes to support laboratory and research applications. No medical or dosing recommendations are implied. Always follow your institution's protocols for handling and administering research peptides. Consult a qualified professional for any clinical applications.