Retatrutide Dosage Calculator
Calculate the exact insulin syringe units for your retatrutide dose. Enter your vial size, bacteriostatic water volume, and weekly dose for an instant, precise reading — for 10 mg, 20 mg, and 30 mg vials.
Also called: retatrutide calculatorretatrutide reconstitution calculatorretatrutide units calculator
Retatrutide dosage chart — mg to syringe units
Look up your retatrutide dose in the left column and find the corresponding units based on your reconstitution concentration. All values use a standard U-100 (1 mL) insulin syringe. Values marked with * exceed one syringe and require split injections — confirm the approach with your prescriber.
| Dose | 10 mg/mL10 mg + 1 mL | 5 mg/mL10 mg + 2 mL | 2.5 mg/mL10 mg + 4 mL | Typical Use |
|---|---|---|---|---|
| 2 mg | 20 units | 40 units | 80 units | Starting dose (weeks 1–4) |
| 4 mg | 40 units | 80 units | 160 units* | Titration dose |
| 6 mg | 60 units | 120 units* | 240 units* | Titration dose |
| 8 mg | 80 units | 160 units* | 320 units* | Maintenance dose |
| 12 mg | 120 units* | 240 units* | 480 units* | Highest trial dose |
* Values exceeding 100 units require splitting into multiple injections. Consult your prescriber for the recommended injection approach at higher doses.
Dosing Calculation Example: Retatrutide 2 mg starting dose
Here is how the calculation works for the most common retatrutide starting setup.
You have a 10 mg vial of retatrutide and add 2 mL of bacteriostatic water. Your starting dose is 2 mg (2,000 mcg) weekly using a 1 mL (100-unit) insulin syringe.
- Concentration: 10 mg ÷ 2 mL = 5.0 mg/mL
- Dose volume: 2,000 mcg ÷ 5,000 mcg/mL = 0.4 mL
- Syringe units: 0.4 mL × 100 = 40 units
- Doses per vial: 10,000 mcg ÷ 2,000 mcg = 5 weekly doses
How to reconstitute retatrutide
Retatrutide is supplied as lyophilized (freeze-dried) powder. Always follow your prescribing clinician's or compounding pharmacy's instructions.
Gather supplies
Retatrutide vial (lyophilized powder), bacteriostatic water (BAC water), sterile U-100 insulin syringes, 70% isopropyl alcohol swabs, and a sharps container.
Bring vials to room temperature
Allow both the retatrutide vial and the bacteriostatic water to sit at room temperature for 15–30 minutes before mixing to prevent foaming and incomplete dissolution.
Swab and inject BAC water slowly
Swab both rubber stoppers with a fresh alcohol swab and let air-dry. Draw the correct BAC water volume and inject slowly into the retatrutide vial, aiming the stream along the inner glass wall at a 45° angle — not directly at the powder.
Gently swirl until clear
Slowly rotate or swirl the vial until the solution is completely clear. Do not shake. A cloudy or particulate solution should not be injected.
Label and refrigerate
Mark the vial with the reconstitution date. Store at 2–8°C (36–46°F). Most reconstituted retatrutide with bacteriostatic water is stable for about 4 weeks refrigerated — follow your pharmacy's specific guidance.
For a complete reconstitution guide covering all peptides, read how to reconstitute peptides. For the full retatrutide protocol, see the retatrutide dosage guide and how much BAC water for retatrutide.
Frequently asked questions
Common questions about retatrutide reconstitution, dose calculations, and syringe units.
How many units is 2 mg of retatrutide?
It depends on your concentration. At 5 mg/mL (10 mg vial + 2 mL BAC water): 2 mg = 0.4 mL = 40 units on a U-100 syringe. At 10 mg/mL (10 mg vial + 1 mL): 2 mg = 0.2 mL = 20 units. Use the calculator above for the exact units for your specific setup.
How much bacteriostatic water do I add to a 10 mg retatrutide vial?
A common setup is 2 mL of bacteriostatic water into a 10 mg retatrutide vial, yielding a 5 mg/mL concentration. At this concentration a 2 mg starting dose equals 40 units on a U-100 syringe. Some prefer 1 mL (10 mg/mL) for smaller injection volumes. Always follow your prescribing provider's specific instructions.
How many units is 4 mg of retatrutide?
At 5 mg/mL (10 mg + 2 mL): 4 mg = 0.8 mL = 80 units. At 10 mg/mL (10 mg + 1 mL): 4 mg = 0.4 mL = 40 units. The calculator above handles any configuration instantly.
How many units is 8 mg of retatrutide?
At 5 mg/mL (10 mg + 2 mL): 8 mg = 1.6 mL — this exceeds a single 1 mL syringe, so you may split into two injections or reconstitute at a higher concentration. At 10 mg/mL (10 mg + 1 mL): 8 mg = 0.8 mL = 80 units. Check your specific setup with the calculator above.
How many units is 12 mg of retatrutide?
12 mg is the highest dose used in retatrutide trials. At 10 mg/mL (10 mg + 1 mL): 12 mg = 1.2 mL — typically split into two injections. At 5 mg/mL (10 mg + 2 mL): 12 mg = 2.4 mL, also split. For high-dose retatrutide, confirm the injection volume and technique with your prescribing clinician.
How long does reconstituted retatrutide last?
Retatrutide reconstituted with bacteriostatic water is typically stable for about 4 weeks when stored refrigerated at 2–8°C (36–46°F). For longer storage, freeze aliquots at -20°C. Always follow your pharmacy's specific stability guidance, which takes precedence over general estimates.
What needle and syringe do I use for retatrutide injections?
Most retatrutide injections are administered subcutaneously using a 29G or 31G insulin syringe with a ½-inch needle. For larger dose volumes (above 0.5 mL), use a 1 mL (100-unit) syringe. Inject into the lower abdomen, thigh, or upper arm, rotating sites with each injection.
What is the difference between retatrutide and tirzepatide dosing?
Retatrutide is a triple GIP/GLP-1/glucagon receptor agonist, while tirzepatide is a dual GIP/GLP-1 agonist. Both are dosed in milligrams and titrated slowly. Retatrutide trials titrated from 2 mg up to 12 mg weekly; tirzepatide from 2.5 mg up to 15 mg. Because dose amounts differ, always confirm your specific dose and concentration with your prescriber.
Is retatrutide FDA-approved?
No. As of 2026 retatrutide is investigational and still in clinical trials — it is not FDA-approved. This calculator is provided for educational purposes only. Any use should be under the supervision of a licensed healthcare provider.
Related tools
Medical Disclaimer: This retatrutide dosage calculator is provided for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. All dosing should be determined and supervised by a licensed healthcare provider. Retatrutide is investigational and not FDA-approved as of 2026. Always consult your prescriber.
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