Compounded tirzepatide dosage calculator
You are trying to work out how much to draw or when to step up.
Reference and calculator, not medical advice. Dosing figures below are transcribed from FDA-approved prescribing information and link back to it. Last reviewed August 2026.
Compounded vials are where this arithmetic actually bites, because the concentration is not standardised. Branded pens are preset and need no conversion at all; a compounded vial can arrive at 5, 10 or 20 mg/mL, and the same prescribed dose is a different mark on the syringe in each case.
mg → syringe units converter
U-100 syringe. Formula: (dose ÷ concentration) × 100.
Check the concentration printed on the vial you are actually holding. The same dose in milligrams is a completely different mark on the syringe at a different concentration. If the number here does not match what your prescriber told you, trust your prescriber.
The rule that prevents the serious mistake: convert using the concentration printed on the vial in your hand, every time, including when you start a new vial. A units figure that was correct for your last vial can be several times the intended dose if the new one is more concentrated.
Zepbound dose → units reference
U-100 syringe units for each labelled dose, at the concentrations commonly supplied.
| Dose | 5 mg/mL | 10 mg/mL | 20 mg/mL |
|---|---|---|---|
| 2.5 mg | 50.0 u | 25.0 u | 12.5 u |
| 5 mg | 100.0 u | 50.0 u | 25.0 u |
| 7.5 mg | 150.0 u | 75.0 u | 37.5 u |
| 10 mg | 200.0 u | 100.0 u | 50.0 u |
| 12.5 mg | 250.0 u | 125.0 u | 62.5 u |
| 15 mg | 300.0 u | 150.0 u | 75.0 u |
Only use the column matching the concentration printed on your vial.
Compounded vs brand-name: what actually differs
Current as of August 2026.
- Prepared by a pharmacy, not the original manufacturer — so there is no FDA-approved label for the exact preparation you receive.
- Much more restricted than during the 2024–25 shortages. Supply is smaller and less predictable than it was.
- Brand-name self-pay programmes have narrowed the price gap that made compounding attractive.
Compounded is usually cheaper but can change with the rules; brand-name costs more and is more predictable. Worth raising with whoever writes your prescription. FDA’s compounding pages have the detail if you want it.
Common questions
- Is the dosing schedule different for compounded tirzepatide?
- A compounded preparation has no label and therefore no schedule of its own. What exists is the branded schedule above, which is what prescribers generally work from. Your prescription is the authority on what you should take.
- Why do concentrations vary at all?
- Because each preparation is made to a pharmacy formulation rather than a single approved specification. That is the defining difference from an approved product, and it is why the number on your vial matters more than any figure you read online.
- My vial says mg/mL but the dose is in units. Which do I trust?
- Neither in isolation — you need both, and the concentration must be the one on that vial. If the two do not reconcile, that is a question for the prescriber or pharmacy before you draw anything.
Common questions
- What is the starting dose of Zepbound?
- The prescribing information lists 2.5 mg once weekly as the starting dose, held for the first four weeks before any increase.
- What is the maximum labelled dose of Zepbound?
- 15 mg once weekly, reached through the stepped schedule shown above.
- How many units is 5 mg at 20 mg/mL?
- 25.0 units on a U-100 syringe. The arithmetic is (dose ÷ concentration) × 100, and it only holds if the concentration on your vial matches.
Sources and last review
Every dosing figure on this page is transcribed from an FDA-approved label and links back to it. Conversions are arithmetic you can repeat by hand. Nothing here is reviewed by a clinician, and this site does not employ one — which is exactly why what I do publish stays traceable to its source.
- Zepbound (Tirzepatide) prescribing information — Eli Lilly, label revised 6 May 2026, checked 7 August 2026
Transcribed from the labels above and checked by me — Gavin, who builds this site, takes a GLP-1, and is not a clinician. Last reviewed August 2026. Found an error? [email protected] — I treat corrections as bugs. How this site is built and funded.
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