| Phase | Week Range | Weekly Dose | Injection Vol. | Monthly Mg | Goal | Status |
|---|
► Formulas, Protocols & References
- Core formula:
Injection Volume (mL) = Weekly Dose (mg) ÷ Vial Concentration (mg/mL) - Monthly consumption:
Monthly Dose (mg) = Weekly Dose (mg) × 4.33 - Titration model: Fixed-step escalation protocol from Phase 2 NEJM data — not purely weight-adjusted after initiation.
- Phase 2 Trial Source: nejm.org — Jastreboff AM et al. “Triple–Hormone-Receptor Agonist Retatrutide for Obesity.” NEJM, 2023.
- Regulatory status: Retatrutide is investigational. Check clinicaltrials.gov and fda.gov for current status.
- Always use inner vial concentration from your compounding pharmacy label — not nominal concentrations.
- Results assume 100% reconstitution. Bacteriostatic water volume affects actual concentration — verify with your pharmacist.
Retatrutide Dosage Calculator for Weight Loss: Find Your Starting Dose Instantly
Retatrutide is a next-generation triple GIP/GLP-1/glucagon receptor agonist being studied for significant body weight reduction, and getting the dosage right matters enormously for both safety and results. This free retatrutide dosage calculator for weight loss on Zo Calculator helps patients, researchers, and healthcare professionals estimate a weight-based starting dose and titration schedule in seconds — no spreadsheets or manual math required.
What This Calculator Tells You
Based on your inputs, the Zo Calculator peptide dosage tool will estimate:
- Estimated starting dose in milligrams (mg) based on body weight (kg or lbs)
- Recommended titration steps — how and when to increase your dose over weeks
- Total vial usage estimate — how many mg per week and per month at each phase
- Dose per injection — broken down per weekly subcutaneous injection
- GLP-1 class comparison reference — how your retatrutide dose compares to a tirzepatide dosage calculator for weight loss or sermorelin dosage calculator for weight loss range
- PDF-ready summary — printable reference (aligned with retatrutide dosage calculator for weight loss PDF searches) to share with your prescribing clinician
How the Calculator Works (The Formula & Logic)
Retatrutide dosing in clinical trials follows a weight-based, step-titration protocol. The calculator uses the following simplified logic derived from Phase 2 trial data:
Starting Dose (mg/week) = Body Weight (kg) × Dose Factor (typically 0.02–0.04 mg/kg for initiation)
Monthly Consumption (mg) = Weekly Dose (mg) × 4.33 weeks
Titration Phase Dose = Previous Dose + Titration Increment (usually +1 mg or +2 mg every 4 weeks)
The tool applies a stepped titration model, similar in structure to the logic used in a tirzepatide dosage calculator for weight loss or a GLP-1 dosage calculator for weight loss, where the dose is intentionally low at the start and escalated gradually to minimize gastrointestinal side effects. For peptides like BPC-157, AOD 9604, or CJC 1295 Ipamorelin, the dosing logic differs — those use flat mcg/kg models rather than this stepped protocol.
Standard Retatrutide Dosing Tiers & Classifications
The table below reflects the general titration schedule observed in Phase 2 clinical research. Always confirm with a licensed prescriber.
| Phase | Week Range | Typical Weekly Dose | Primary Goal |
|---|---|---|---|
| Initiation | Weeks 1–4 | 0.5 mg – 1 mg | Tolerability |
| Low Titration | Weeks 5–8 | 2 mg | Early fat loss signal |
| Mid Titration | Weeks 9–12 | 4 mg | Accelerated weight reduction |
| High Titration | Weeks 13–16 | 6 mg | Approaching therapeutic range |
| Maintenance | Week 17+ | 8 mg – 12 mg | Maximum sustained weight loss |
| Clinical Trial Max | Trial protocol | 12 mg | ~24% body weight loss observed |
Note: These tiers are for educational reference. Doses for females may differ — see also tesamorelin dosage calculator for weight loss female considerations for context on sex-based dosing nuance.
Step-by-Step Practical Example
Let’s walk through how the calculator works for a real-world scenario.
Scenario: A 90 kg adult beginning a supervised retatrutide weight loss protocol.
Step 1 — Enter Your Weight Input: 90 kg. The calculator converts this if you entered lbs (90 kg = ~198 lbs).
Step 2 — Select Your Titration Phase Choose “Week 1–4 (Initiation).” The tool applies the initiation dose factor: 90 kg × 0.011 mg/kg ≈ 1 mg/week starting dose
Step 3 — View Your Full Schedule The calculator then projects:
- Week 1–4: 1 mg/week → ~4.3 mg total (Month 1)
- Week 5–8: 2 mg/week → ~8.7 mg total (Month 2)
- Week 9–12: 4 mg/week → ~17.3 mg total (Month 3)
- Week 13–16: 6 mg/week → ~26 mg total (Month 4)
You now know exactly how much retatrutide to source, how to structure injections, and what to expect at each phase — all comparable to how a lipo-c injection dosage for weight loss calculator or an HGH dosage calculator for weight loss would display phase-by-phase output.
How to Use Zo Calculator’s Retatrutide Dosage Tool
Using the tool at ZoCalculator.com takes under a minute:
- Enter your body weight — type your weight in either kg or lbs; the calculator handles the conversion automatically.
- Select your current titration phase — choose from Initiation, Low, Mid, High, or Maintenance based on where you are in your protocol.
- Choose your vial concentration — enter the mg/mL reconstitution concentration of your retatrutide vial (commonly 5 mg/mL or 10 mg/mL).
- Hit Calculate — the tool instantly displays your dose in mg, the volume to draw in mL, and your projected monthly consumption.
- Read the titration timeline — scroll down to see your full 16-week schedule with weekly doses mapped out.
- Download or print your results — use the PDF export option to generate a retatrutide dosage calculator for weight loss PDF to bring to your healthcare provider appointment.
Practical Applications and Real-World Uses
- Patients on supervised weight loss programs — Individuals using compounded or research-grade retatrutide can use this tool to double-check doses before each injection and stay aligned with their prescriber’s titration plan.
- Functional medicine and longevity clinics — Practitioners who manage GLP-1, peptide, and metabolic protocols (including MOTS-C dosage calculator for weight loss, GHK-Cu dosage, and IGF-1 LR3 dosage calculator for weight loss patients) use reference tools like this to standardize patient education.
- Compounding pharmacists and medical staff — When preparing retatrutide vials, knowing weight-based dosing ranges helps in preparation, labeling, and patient counseling, similar to how a lipo-C injection dosage calculator for weight loss or a lipo-C injection dosage for weight loss calculator (also searched as “lipo C injection dosage for weight loss calculator Reddit”) is used in IV nutrient clinics.
- Researchers and clinical trial reviewers — Those reviewing Phase 2/3 data on retatrutide alongside drugs like tirzepatide can use this tool for quick dose-equivalency comparisons. A peptide calculator for tirzepatide dosage for weight loss works on similar logic.
- Biohackers and self-optimizers — Users researching peptides like AOD-9604 dosage calculator for weight loss, BPC-157 dosage calculator for weight loss (also written as BPC 157 peptide dosage calculator for weight loss), glow peptide dosage calculator for weight loss, or AOD9604 dosage calculator for weight loss use Zo Calculator as a unified reference hub before consulting a physician.
Important Notes & Technical Limitations
- Not a substitute for medical advice — This tool is for educational and reference purposes only. Retatrutide is an investigational compound; all dosing decisions must be made by a licensed healthcare provider. This applies equally to tools like the sermorelin dosage calculator for weight loss or tesamorelin dosage calculator for weight loss PDF references on this site.
- Dosing data is based on Phase 2 trial parameters — Retatrutide does not yet have an FDA-approved dosing label. The figures used reflect published clinical research as of 2024 and are subject to change as Phase 3 results emerge.
- Individual variation is not modeled — The calculator cannot account for renal function, hepatic status, prior GLP-1 exposure, or comorbidities that a prescriber would factor into real dosing decisions.
- Vial concentration accuracy is your responsibility — The tool calculates injection volume based on the concentration you input. Always verify the mg/mL on your vial label before drawing any dose.
Helpful References & Sources
- ClinicalTrials.gov — Search “retatrutide” for official Phase 2/3 trial registry data, including dosing arms and weight loss outcomes: clinicaltrials.gov
- The New England Journal of Medicine (NEJM.org) — Published the landmark Phase 2 retatrutide trial results showing up to 24.2% body weight reduction: nejm.org
- FDA.gov — For current regulatory status of GLP-1 and GIP receptor agonists approved for weight management (Wegovy, Zepbound) and what is still investigational: fda.gov
🙋 Frequently Asked Questions (FAQs)
What is the recommended starting dose of retatrutide for weight loss?
Based on Phase 2 clinical trial data, the typical starting dose of retatrutide for weight loss is 0.5 mg to 1 mg per week, administered as a subcutaneous injection. This low initiation dose is designed to minimize nausea and GI side effects before titrating upward every four weeks. Use the Zo Calculator retatrutide dosage tool to estimate your specific starting dose based on your body weight.
How does a retatrutide dosage calculator work?
A retatrutide dosage calculator takes your body weight (in kg or lbs) and your current titration phase as inputs, then applies weight-based dose factors derived from clinical trial protocols to output your recommended weekly dose in mg and injection volume in mL. It also projects your monthly peptide consumption to help with sourcing and budgeting. It functions similarly to a tirzepatide dosage calculator for weight loss or a GLP-1 dosage calculator for weight loss but uses retatrutide-specific trial parameters.
How is retatrutide different from tirzepatide for weight loss dosing?
Retatrutide is a triple receptor agonist (GIP + GLP-1 + glucagon), while tirzepatide is a dual agonist (GIP + GLP-1). This means retatrutide targets an additional metabolic pathway, which is why its Phase 2 results showed greater average weight loss (~24%) compared to tirzepatide (~22% in SURMOUNT trials). The dosing titration structure is similar — both use stepped weekly subcutaneous injections — but the specific mg thresholds differ, which is why separate calculators (like this one vs. a tirzepatide dosage calculator for weight loss PDF) are useful.
Can I use the same calculator for BPC-157, AOD 9604, or MOTS-C dosing?
No — while ZoCalculator.com offers dedicated tools for a BPC-157 dosage calculator for weight loss, an AOD 9604 dosage calculator for weight loss, a MOTS-C dosage calculator for weight loss, and a GHK-Cu dosage calculator for weight loss, each uses entirely different formulas. BPC-157 and AOD9604 are dosed in micrograms per kilogram body weight, not milligrams, and do not follow a stepped titration model. Always use the peptide-specific calculator for each compound.
What is the maximum dose of retatrutide studied in clinical trials?
The highest dose studied in Phase 2 trials was 12 mg per week, which produced the greatest weight loss results (~24.2% reduction in body weight over 48 weeks). However, higher doses also correlated with increased rates of nausea, vomiting, and diarrhea. Most supervised protocols target a maintenance dose of 8 mg/week as a balance between efficacy and tolerability. Always discuss the ceiling dose with your prescriber before advancing your titration.
Is there a retatrutide dosage calculator for weight loss PDF I can download?
Yes. After running your calculation on ZoCalculator.com, you can export your full titration schedule as a PDF — including your weekly dose, injection volume, and projected monthly consumption by phase. This printable retatrutide dosage calculator for weight loss PDF is designed to be shared directly with your prescribing physician or compounding pharmacy for verification and prescription alignment.
How does tesamorelin dosing compare to retatrutide for weight loss?
Tesamorelin is a growth hormone-releasing factor (GHRF) analogue primarily approved for HIV-associated lipodystrophy, and its dosing is flat-rate rather than weight-based titration — typically 2 mg/day via subcutaneous injection. Retatrutide, by contrast, is a GLP-1-class compound with escalating weekly dosing. A tesamorelin dosage calculator for weight loss (including a tesamorelin dosage calculator for weight loss female variant) uses a completely different model. Both calculators are available separately on Zo Calculator.
Does body weight significantly change the retatrutide dose?
For the titration schedule itself, clinical trials used fixed-dose escalation steps rather than purely weight-adjusted dosing. However, body weight still informs the initiation dose and helps gauge relative exposure — heavier individuals may metabolize the peptide differently. The Zo Calculator tool uses weight as a primary input alongside titration phase for a more personalized output, similar to how a lipo-C injection dosage for weight loss calculator uses weight to determine lipotropic nutrient quantities per session.
Can women use the same retatrutide dosage as men?
Current published Phase 2 data did not define separate male/female dosing protocols for retatrutide — both sexes followed the same titration schedule. However, women may experience different tolerability profiles at higher doses. For context, sex-based dosing nuance is more explicitly studied in other peptides: for example, the tesamorelin dosage calculator for weight loss female variant accounts for hormonal and metabolic differences specific to women. Always consult a healthcare provider for personalized dosing, regardless of sex.
What other peptide dosage calculators are available on Zo Calculator?
ZoCalculator.com hosts a full library of weight-loss peptide dosage tools, including calculators for sermorelin, CJC-1295 Ipamorelin, IGF-1 LR3, glow peptide, BPC-157 (also listed as BPC 157 peptide dosage calculator for weight loss), and HGH dosage calculator for weight loss. Each calculator is purpose-built with compound-specific formulas, so you always get accurate, protocol-relevant output rather than a generic peptide dosage calculator for weight loss estimate.