Retatrutide Dosage Calculator
Plan a full Retatrutide titration schedule or calculate a single dose. Get exact injection volume, insulin units, and weeks-per-vial for the 5 mg → 30 mg vial range.
Retatrutide vials. Stacks with bulk pricing.
U-100 · 1 mL Visualizer
100 UNITS = 1 MLTitration Schedule
First 24 weeks · current = week 1Full Titration Schedule
Target 8 mg/week at 4 weeks per step. Highlighted row = your current week.
| Phase | Weeks | Dose | Volume / wk | IU / wk |
| Titration · Step 1CURRENT | Wk 1–4 | 1 mg | 0.200 mL | 20.0 IU |
| Titration · Step 2 | Wk 5–8 | 2 mg | 0.400 mL | 40.0 IU |
| Titration · Step 3 | Wk 9–12 | 4 mg | 0.800 mL | 80.0 IU |
| Maintenance | Wk 13–16 | 8 mg | 1.600 mL | 160.0 IU |
Each titration step gives your gut time to adapt — Phase 2 trials showed jumping from 2 mg straight to 4 mg roughly doubled GI side effect rates.
Research Use Only
Retatrutide is an investigational GLP-1/GIP/glucagon triple agonist still in Phase 3 trials and is not approved by the FDA. This calculator is for educational and research purposes only. Consult a qualified clinician before any use.
How the Retatrutide Dosage Calculator Works
Retatrutide is a triple agonist of the GLP-1, GIP, and glucagon receptors, currently the most potent weight-loss peptide in clinical trials. Unlike body-weight-dosed peptides like BPC-157, Retatrutide uses a fixed titration ladder: you start low and step the dose up every few weeks until you reach your maintenance dose.
This calculator runs in two modes. Titration Schedule mode asks for your target maintenance dose (4 mg, 8 mg, or 12 mg), titration speed (standard 4-week steps or slow 6-week steps for GI-sensitive users), and current week of your protocol. It outputs the exact dose for this week plus the full schedule, the per-injection volume, and the U-100 insulin syringe tick mark to draw to. Simple Dose mode skips the schedule — enter any weekly dose and get instant volume and IU output.
Retatrutide Titration Reference
The Phase 2 trial-derived protocol most clinicians follow. Each step is four weeks unless you extend to six weeks for GI tolerance.
| Phase | Weeks | Weekly Dose | Notes |
| Start | 1–4 | 1 mg | Body adapts; minimal effects |
| Step 1 | 5–8 | 2 mg | Watch for GI symptoms |
| Step 2 | 9–12 | 4 mg | Noticeable appetite suppression |
| Step 3 | 13–16 | 8 mg | Significant weight loss begins |
| Maintenance | 17+ | 12 mg | Maximum studied dose |
Phase 2 trial data showed average body weight reduction of 24.2% at the 12 mg dose over 48 weeks — the largest weight loss recorded for any peptide therapy.
Retatrutide Reconstitution Quick Reference
Common vial-and-water combinations. Use the calculator above for your exact configuration.
| Vial | BAC Water | Concentration | 2 mg dose | 4 mg dose | 8 mg dose |
| 5 mg | 1 mL | 5 mg/mL | 0.4 mL (40 IU) | 0.8 mL (80 IU) | 1.6 mL (160 IU) |
| 10 mg | 2 mL | 5 mg/mL | 0.4 mL (40 IU) | 0.8 mL (80 IU) | 1.6 mL (160 IU) |
| 10 mg | 1 mL | 10 mg/mL | 0.2 mL (20 IU) | 0.4 mL (40 IU) | 0.8 mL (80 IU) |
| 20 mg | 2 mL | 10 mg/mL | 0.2 mL (20 IU) | 0.4 mL (40 IU) | 0.8 mL (80 IU) |
| 30 mg | 3 mL | 10 mg/mL | 0.2 mL (20 IU) | 0.4 mL (40 IU) | 0.8 mL (80 IU) |
Retatrutide Dosing FAQ
01How do you calculate Retatrutide dosage?
Retatrutide is dosed by weekly titration, not by body weight. The standard protocol starts at 1 mg per week and steps up every 4 weeks: 1 mg → 2 mg → 4 mg → 8 mg → 12 mg. Your weekly dose depends on which step you are on. The calculator above runs the full schedule for you and shows the exact injection volume based on your vial size and BAC water volume.
02What is the standard Retatrutide titration schedule?
The Phase 2 trial-derived protocol uses four-week steps. Weeks 1–4 at 1 mg, weeks 5–8 at 2 mg, weeks 9–12 at 4 mg, weeks 13–16 at 8 mg, and weeks 17+ at 12 mg (maintenance). If you only need a 4 mg or 8 mg maintenance dose, the schedule ends earlier. People sensitive to GI side effects often extend each step to 6 weeks.
03What is the maximum Retatrutide dose?
12 mg per week is the maximum dose tested in Phase 2 clinical trials. At that dose, average body weight reduction reached 24.2% over 48 weeks — the largest weight loss recorded for any peptide therapy to date. Doses above 12 mg per week have not been studied for safety.
04How much Retatrutide do I draw from a 10 mg vial?
It depends on how much BAC water you reconstitute with. A 10 mg vial mixed with 2 mL of BAC water gives a 5 mg/mL concentration. At a 4 mg weekly dose, you draw 0.8 mL (80 IU on a U-100 syringe). At 2 mg, you draw 0.4 mL (40 IU). The calculator above renders the exact tick mark for any dose.
05How many weeks does a Retatrutide vial last?
A 10 mg vial yields 10 weeks at 1 mg, 5 weeks at 2 mg, 2.5 weeks at 4 mg, or about 1.25 weeks at 8 mg. A 20 mg vial doubles all of those numbers. The calculator shows doses-per-vial and weeks-per-vial for your exact configuration so you can plan reorders.
06Why does Retatrutide use such a gradual titration?
Retatrutide activates three different gut hormone receptors (GLP-1, GIP, and glucagon), each of which affects digestion. In Phase 2 trials, participants who started at 4 mg instead of 2 mg experienced nearly double the rate of GI symptoms — nausea, vomiting, diarrhea, abdominal pain. The gradual ramp-up lets your gut adapt and significantly reduces dropout rates.
07Can I skip ahead in the titration if I feel fine?
Most clinicians advise against it. The cumulative effect of receptor activation builds over weeks — early-week tolerance doesn't predict how you'll respond at higher doses. The four-week step is a safety cushion. If your provider supervises you, an accelerated schedule is possible, but it carries materially higher side-effect risk.
08What day of the week should I inject Retatrutide?
Pick any day and stay consistent. Many users prefer Sunday or Monday evening — that way the peak GI effects (24–48 hours post-injection) overlap with home time rather than the workweek. Retatrutide's ~6-day half-life means the dose stays relatively steady through the week regardless of which day you choose.
09How does Retatrutide dosage compare to Tirzepatide or Semaglutide?
All three are titrated weekly. Semaglutide tops out at 2.4 mg/week, Tirzepatide at 15 mg/week, and Retatrutide at 12 mg/week — but the mg values are not directly comparable because each molecule has different receptor affinity. What matters is the relative weight-loss data: Retatrutide 12 mg at 48 weeks (~24%) outperforms Tirzepatide 15 mg at 72 weeks (~22%) and Semaglutide 2.4 mg at 68 weeks (~15%).
10Is the Retatrutide dosage calculator accurate?
The math is exact: dose (mg) ÷ concentration (mg/mL) = injection volume (mL), then × 100 for insulin units. The titration schedule mirrors the Phase 2 trial protocol. All output is for educational and research purposes. Retatrutide is not yet FDA-approved; consult a qualified clinician before any use.
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All tools are for research and educational purposes only. Not medical advice.
