Wegovy vs Zepbound Dosing Compared

Wegovy and Zepbound are both FDA-approved once-weekly injections for chronic weight management, but they are different molecules on different dose scales: Wegovy is semaglutide, titrated 0.25 → 0.5 → 1 → 1.7 → 2.4 mg weekly, while Zepbound is tirzepatide, titrated 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg weekly. In the head-to-head SURMOUNT-5 trial Zepbound produced greater average weight loss than Wegovy, but the two are not interchangeable milligram-for-milligram, and the syringe units you draw from a compounded vial depend on the vial concentration — not on the brand name.

TL;DR — key takeaways

• Same job, different molecules. Wegovy = semaglutide (single GLP-1 agonist); Zepbound = tirzepatide (dual GIP/GLP-1 agonist). Both are the weight-management brands, distinct from the diabetes brands Ozempic and Mounjaro.
• Different number lines. Wegovy maxes at 2.4 mg/week; Zepbound maxes at 15 mg/week. A bigger milligram number does not mean a bigger “dose” — the scales are not comparable.
• Head-to-head data. In SURMOUNT-5, the only direct trial, the highest-tolerated Zepbound dose beat the highest-tolerated Wegovy dose on average weight loss.
• Units follow concentration. Whether you draw 30, 40, or 75 units depends on your vial’s mg/mL strength, which is exactly what a reconstitution or units calculator solves for you.

Wegovy vs Zepbound: the brands, not just the molecules

The brand layer trips people up because each molecule is sold under two names for two indications. Semaglutide is Ozempic for type 2 diabetes and Wegovy for weight management; tirzepatide is Mounjaro for diabetes and Zepbound for weight management. So a Wegovy-vs-Zepbound question is really a weight-management question, and both products are approved for adults with obesity (BMI ≥ 30) or overweight (BMI ≥ 27) plus a weight-related condition.

Their approved indications have also branched out. Wegovy carries an added indication to reduce the risk of major cardiovascular events in adults with established cardiovascular disease and obesity, based on the SELECT trial. Zepbound is additionally approved to treat moderate-to-severe obstructive sleep apnea in adults with obesity, based on SURMOUNT-OSA. That divergence matters when a prescriber chooses between them — the decision is rarely about weight loss alone.

Side-by-side: dosing and profile

Figures reflect the FDA-approved Wegovy and Zepbound labels for chronic weight management. Maintenance doses of 1.7 mg are available for Wegovy and 5 mg or 10 mg for Zepbound when a patient cannot tolerate the top rung; your prescriber sets the target.

The titration staircase

Both labels increase the dose no sooner than every four weeks, holding each rung long enough for the gastrointestinal side effects — nausea, reflux, and altered bowel habits — to settle before climbing. Rushing the staircase is the most common reason people abandon either drug, so the schedule is part of the dose, not an afterthought. Reaching a Wegovy maintenance dose takes roughly 16–20 weeks; a full Zepbound climb to 15 mg can take 20 weeks or more.

What the head-to-head trial showed

SURMOUNT-5 randomised adults with obesity (without diabetes) to the maximum-tolerated dose of tirzepatide (Zepbound) or semaglutide (Wegovy) over 72 weeks. Tirzepatide produced a larger average percentage weight loss than semaglutide. That is a population average, not a guarantee for any one person, and it does not make Zepbound “stronger” in a way that maps onto milligrams — it reflects the dual-receptor mechanism and the different dose ranges. Tolerability, cost, insurance coverage, and the extra indications often decide the choice in practice.

How to turn each dose into syringe units

Branded Wegovy and Zepbound ship as fixed-dose pens or single-dose vials, so there is no maths to do. But many people use compounded multi-dose vials and must draw the dose themselves. On a U-100 insulin syringe there are 100 units per 1 mL, so the conversion is always the same regardless of brand: find the concentration (mg/mL), divide your dose by it to get mL, then multiply by 100 to get units.

Dose-to-units reference chart

Maintenance doses for each brand shown as units on a U-100 syringe at two common compounded concentrations. Always confirm against your own vial label.

Notice how the higher Zepbound doses overflow a 1 mL syringe at 5 mg/mL — those doses need a more concentrated vial. Wegovy’s lower milligrams comfortably fit at either strength.

A U-100 syringe, two doses

The same 100-unit barrel holds both brands. Here a 30-unit Wegovy draw and a 75-unit Zepbound draw are marked on the identical syringe scale.

How this is calculated

Every number here rests on two facts: a U-100 syringe holds 100 units per mL, and concentration is dose divided by volume. There is no brand-specific constant — the arithmetic is identical for Wegovy, Zepbound, or any vialled peptide, which is why the same calculator serves both. None of this is medical advice; it is the maths behind a dose and a brand your prescriber has chosen. Efficacy figures are summarised from published trials and describe averages, not individual outcomes.

Frequently asked questions