Free retatrutide reconstitution calculator. Enter vial size (5-15 mg), BAC water volume, and weekly dose to get concentration, syringe units, and doses per vial. Includes the Phase 2/3 trial titration protocol (1-12 mg weekly), triple-agonist dosing reference, and comparison with tirzepatide. Verify retatrutide quality with independent lab test data on Peptigrity.
The Phase 2 trial (Jastreboff et al., NEJM 2023, n=338) established a 4-week step-up escalation from 2 mg to 12 mg. Participants who started at higher doses or escalated too quickly experienced nearly double the rate of gastrointestinal side effects. Phase 3 TRIUMPH trials evaluate 4 mg, 9 mg, and 12 mg as maintenance targets.
| Titration Tier | Weekly Dose | Weeks | At 6 mg/mL | At 10 mg/mL | At 20 mg/mL |
|---|---|---|---|---|---|
| Tier 1 (starting) | 2 mg | Weeks 1-4 | ~33 units | 20 units | 10 units |
| Tier 2 | 4 mg | Weeks 5-8 | ~67 units | 40 units | 20 units |
| Tier 3 | 8 mg | Weeks 9-12 | Exceeds 100u | 80 units | 40 units |
| Tier 4 (Phase 2 max) | 12 mg | Week 13+ | Exceeds 100u | Exceeds 100u | 60 units |
| Phase 3 targets | 9 mg | Maintenance | Exceeds 100u | 90 units | 45 units |
At 20 mg/mL (20 mg vial + 1 mL, or 30 mg vial + 1.5 mL), the entire titration schedule through 12 mg fits within 60 units - the cleanest measurement. The calculator flags syringe capacity warnings automatically.
Step 1 - Choose BAC Water Volume. For the full titration through 12 mg in a single draw, target 20 mg/mL (e.g. 20 mg vial + 1 mL BAC water). At 10 mg/mL, doses up to 10 mg fit within 100 units. The BAC water calculator recommends volumes based on your dose and syringe.
Step 2 - Reconstitute. Inject BAC water slowly against the inside glass wall. Retatrutide dissolves within 1-3 minutes of gentle swirling. Solution should be clear and colourless. See reconstituting peptides step by step.
Step 3 - Store. Refrigerate at 2-8°C. Stable for approximately 28 days. See how to store peptides.
| Factor | Retatrutide | Tirzepatide | Semaglutide |
|---|---|---|---|
| Receptor targets | Triple: GLP-1 + GIP + Glucagon | Dual: GIP + GLP-1 | GLP-1 only |
| Starting dose | 2 mg weekly | 2.5 mg weekly | 0.25 mg weekly |
| Maximum dose | 12 mg weekly | 15 mg weekly | 2.4 mg weekly |
| Phase 2 weight loss (48 wk) | 24.2% at 12 mg | 22.5% at 15 mg | 15.8% at 2.4 mg |
| Common vial sizes | 5, 10, 12, 20, 30 mg | 5, 10, 15, 30, 60 mg | 2, 3, 5, 10 mg |
| Regulatory status | Phase 3 (not yet approved) | FDA-approved (Mounjaro/Zepbound) | FDA-approved (Ozempic/Wegovy) |
Retatrutide's glucagon receptor activity adds thermogenesis and hepatic fat reduction that dual-agonists lack - but it also carries a different side effect profile. For compound-specific calculators, see the tirzepatide calculator and semaglutide calculator.
| Vial Size | At 2 mg/wk | At 4 mg/wk | At 8 mg/wk | At 12 mg/wk |
|---|---|---|---|---|
| 5 mg | 2.5 weeks | 1.25 weeks | - | - |
| 10 mg | 5 weeks | 2.5 weeks | 1.25 weeks | - |
| 12 mg | 6 weeks | 3 weeks | 1.5 weeks | 1 week |
| 20 mg | 10 weeks | 5 weeks | 2.5 weeks | ~1.7 weeks |
| 30 mg | 15 weeks | 7.5 weeks | 3.75 weeks | 2.5 weeks |
Reconstituted retatrutide lasts approximately 28 days. For price comparisons, use the cost-per-dose calculator.
| Tool | What It Does |
|---|---|
| Peptide Reconstitution Calculator | Standard calculator for all 30+ peptides |
| Tirzepatide Calculator | Tirzepatide-specific with 6-tier titration |
| Semaglutide Calculator | Semaglutide-specific with dose escalation |
| Cost-per-Dose Calculator | Compare retatrutide costs across vendors |
| BAC Water Calculator | Optimal BAC water volume for your vial and dose |
| Purity Comparison Tool | Compare lab-tested purity across brands |
At 6 mg/mL (12 mg vial + 2 mL BAC water): ~33 units. At 10 mg/mL: 20 units. At 20 mg/mL: 10 units. Use the calculator above with your specific vial and BAC water volume for exact numbers.
Phase 2 protocol: 2 mg weekly for weeks 1-4, 4 mg for weeks 5-8, 8 mg for weeks 9-12, and 12 mg from week 13 onward. Phase 3 TRIUMPH trials evaluate 4, 9, and 12 mg as maintenance targets.
2 mL produces 6 mg/mL - practical for starting doses but exceeds syringe capacity above 6 mg. 1 mL produces 12 mg/mL - covers doses up to 12 mg in 100 units. The BAC water calculator recommends volumes based on your dose and syringe.
Retatrutide is a triple-agonist targeting GLP-1, GIP, and glucagon receptors simultaneously. Tirzepatide is a dual-agonist (GIP + GLP-1 only). Retatrutide's glucagon receptor activity adds thermogenesis and hepatic fat reduction. In Phase 2 trials, 12 mg retatrutide achieved 24.2% weight loss at 48 weeks - the highest reported for any injectable.
This calculator is for educational and research purposes only and does not constitute medical advice. Retatrutide is an investigational compound currently in Phase 3 clinical trials (TRIUMPH program) and is not yet approved by the FDA. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.