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.

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Tirzepatide dosing for weight loss in units

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.

Units are a measurement on the syringe, not a dose. The conversion is (dose in mg ÷ vial concentration in mg/mL) × 100 on a U-100 syringe. Everything below follows from that one formula — and the reason it causes so much trouble is that the answer changes completely with concentration.

Three U-100 syringe scales, one for each vial concentration. The same tirzepatide dose lands at a different mark on each: 5 mg is 100 units at 5 mg/mL, 50 units at 10 mg/mL and 25 units at 20 mg/mL. On the 5 mg/mL scale every dose above 5 mg — 7.5, 10, 12.5 and 15 mg — works out at 150 to 300 units, past the 100 unit end of a 1 mL syringe, and on the 10 mg/mL scale 12.5 mg and 15 mg do the same at 125 and 150 units. The table below gives all six doses at all three concentrations. — The same six doses on three different vials. Only the concentration printed on your own vial decides which scale applies to you — and on a 5 mg/mL vial, every dose above 5 mg runs past the end of a 1 mL syringe.

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.

Look across any row. A 5 mg dose is 100 units at 5 mg/mL, 50 units at 10 mg/mL, and 25 units at 20 mg/mL. Same dose, three completely different marks. If someone tells you their dose in units without stating the concentration, that number is unusable.

mg → syringe units converter

U-100 syringe. Formula: (dose ÷ concentration) × 100.

MedicationDose (mg)

Vial concentration (mg/mL)

12.5units on a U-100 syringe

= 0.125 mL · 2.5 mg at 20 mg/mL

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.

Zepbound titration schedule

Tirzepatide · once weekly · subcutaneous injection · as published in the prescribing information

Step	Dose	Notes
Weeks 1–4	2.5 mg	Starting dose — not intended for weight loss effect
Weeks 5–8	5 mg	—
Weeks 9–12	7.5 mg	—
Weeks 13–16	10 mg	—
Weeks 17–20	12.5 mg	—
Week 21+	15 mg	Maximum dose

This is the labelled default. Holding at a step longer than shown is common practice and is a decision for your prescriber. Transcribed from the Zepbound prescribing information (label revised 6 May 2026); checked against that label on 7 August 2026.

Common questions

How many units is 5 mg of tirzepatide?: It depends entirely on concentration: 100 units at 5 mg/mL, 50 units at 10 mg/mL, 25 units at 20 mg/mL. There is no single correct answer without the concentration on your vial.
What is a U-100 syringe?: A syringe calibrated so that 100 units equals 1 mL. It was designed for insulin, which is why the units markings exist at all. If your syringe is not U-100, none of these conversions apply.
My pen does not show units — why?: Pens deliver a preset dose and have no units scale. The units question only arises when drawing from a vial with a syringe.
I switched vials and my usual units number feels wrong.: If the concentration changed, it is wrong. Reconvert from the new label before drawing anything. This is the single most common dosing error in compounded supply.

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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Tirzepatide dosing for weight loss in units

Common questions

Common questions

Sources and last review

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