tirz dosing is mostly about respecting the titration schedule and reading sulfur-burp signals, the math is the easy part. Branded tirz (Mounjaro, Zepbound) ships in pre-filled pens with doses already locked, no calculation needed. Compounded tirz (where it's still legally available via 503A pharmacies for documented clinical need) ships as lyo powder in multi-dose vials, and you reco and draw each dose yourself. This page covers the exact vial sizes, BAC volumes, and slin-pin unit targets for the standard SURMOUNT titration ladder, plus a free calculator pre-filled with a typical compounded protocol.
Key Takeaways
- —Compounded tirz typically ships in 30 mg, 40 mg, or 60 mg vials. 2 mL BAC water is the most common reco volume.
- —At 30 mg + 2 mL the concentration is 15 mg/mL (15,000 mcg/mL). A 2.5 mg starting dose = 0.167 mL = 17 units on a U-100 slin pin.
- —Standard ladder: 2.5 mg weekly x 4 wk → 5 mg x 4 wk → 7.5 mg x 4 wk → 10 mg x 4 wk → 12.5 mg x 4 wk → 15 mg. Don't skip the 4-week step, your gut won't thank you.
- —A single 30 mg vial gives you 12 doses at 2.5 mg, 6 at 5 mg, 4 at 7.5 mg, or 3 at 10 mg.
- —Compounded tirz access is restricted following the FDA shortage-list removal (tirzepatide vs semaglutide guide).
| Vial Size | BAC Water | Concentration | Typical Use |
|---|---|---|---|
| 10 mg | 1 mL | 10 mg/mL | Small starter vials (rare) |
| 30 mg | 2 mL | 15 mg/mL | Most common for titration weeks 1–16 |
| 40 mg | 2 mL | 20 mg/mL | Higher-concentration option |
| 60 mg | 3 mL | 20 mg/mL | High-volume protocols, fewer refills |
The 30 mg / 2 mL reco is the practical default. Concentration is high enough that even a 2.5 mg dose stays above the 0.1 mL small-volume threshold where slin-pin marks start lying to you.
Using the standard 30 mg vial + 2 mL BAC water = 15,000 mcg/mL:
| Titration Week | Weekly Dose | Draw Volume | U-100 Units |
|---|---|---|---|
| 1–4 | 2.5 mg | 0.167 mL | 17 units |
| 5–8 | 5 mg | 0.333 mL | 33 units |
| 9–12 | 7.5 mg | 0.500 mL | 50 units |
| 13–16 | 10 mg | 0.667 mL | 67 units |
| 17–20 | 12.5 mg | 0.833 mL | 83 units |
| 21+ | 15 mg | 1.000 mL | 100 units (full pin) |
A U-100 slin pin is 100u = 1 mL, so above ~50 units you're still inside its range, but a lot of people switch to a 1 mL tuberculin syringe at the 12.5 mg and 15 mg steps to cut the risk of an incomplete draw. Rotate sites, abdomen one week, thigh the next, keep notes on which side is sore.
A note that catches a lot of first-time compounded users out: the brand pen and the compounded vial use different concentrations. A Zepbound pen is dosed in mg, but the cartridge is a different mg/mL than your reco'd vial. Don't carry numbers across. Always recalculate when you switch from pen to vial or change vial size, the math doesn't survive the swap.
Walking the full 20-week titration to a maintenance dose takes the following vial counts:
| Target Maintenance | Total mg Through Week 20 | 30 mg Vials | 60 mg Vials |
|---|---|---|---|
| 5 mg maintenance | 30 mg titration + 10 mg × remaining = 30 + 520 = varies | ~18 | ~9 |
| 10 mg maintenance | 50 mg titration + 10 mg × remaining | ~35 | ~18 |
| 15 mg maintenance | 90 mg titration + 15 mg × remaining | ~50+ | ~25+ |
For year-one planning: someone holding at 10 mg maintenance burns ~520 mg of tirz over 52 weeks (10 mg × 52), which is 18 × 30 mg vials or 9 × 60 mg vials beyond the titration phase.
Worth flagging here, plenty of people stall and end up holding a dose for an extra few weeks rather than stepping up. "Stalled at 5 mg, holding for 3 weeks" is a normal pattern when food noise is already quiet and the scale's still moving. If GW is in sight you don't need to push to 15 mg just because the schedule says so. Cost math for compounded access at ~$229–349/month vs branded Zepbound at $1,060/month is in the tirzepatide vs semaglutide guide.
The Next Pep calculator opens pre-filled with tirz's first titration step.
Other common presets:
Reco'd tirz holds 28 days at 2–8 °C, same as most peptides. Don't freeze. Branded Zepbound and Mounjaro pens have specific manufacturer stability data on the label, follow it. Compounded tirz follows the standard 28-day refrigerated rule.
For a compounded 30 mg vial reco'd with 2 mL BAC water (15 mg/mL): the 2.5 mg starting dose is roughly 17 units on a U-100 slin pin. Each titration step bumps it: 33 / 50 / 67 / 83 / 100 units as you walk through 5 / 7.5 / 10 / 12.5 / 15 mg.
No. The 4-week-per-step schedule is the whole point, it's there to dial down GI side effects (nausea, sulfur burps, the occasional split-dose request from people whose first week was rough). Skipping steps spikes dropout risk without giving you any extra weight loss. Stay on the SURPASS / SURMOUNT cadence even if you feel fine.
2 mL is the most common, gives you 15 mg/mL. Some protocols use 1.5 mL for 20 mg/mL to cut injection volume at higher doses. The calculator handles both, just update the BAC value.
Mostly restricted. The FDA called the tirz shortage over in late 2024, which ended broad 503A compounding. Narrow exceptions remain for documented clinical need. For most cash-pay people, Lilly's direct-from-manufacturer program runs ~$499/month, the cheapest legal route right now. Full breakdown in the tirzepatide vs semaglutide guide.
At the standard 30 mg / 2 mL (15,000 mcg/mL) concentration: 10 mg = 0.667 mL = 67 units on a U-100 slin pin. The calculator shows it directly.
This article is for research and informational purposes only. Tirzepatide is an FDA-regulated prescription medication. Compounded tirzepatide access is restricted following the FDA's February 2026 shortage-list decision. Consult a licensed healthcare professional for any tirzepatide protocol.
Research Disclaimer. All content on Next Pep is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Consult a licensed healthcare professional before considering any peptide protocol.
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