Semaglutide vs Tirzepatide Dosing Compared

Semaglutide and tirzepatide both start low and step up every four weeks, but they run on completely different number lines: semaglutide climbs 0.25 → 0.5 → 1 → 1.7 → 2.4 mg weekly, while tirzepatide climbs 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg weekly. They are not interchangeable milligram-for-milligram, and the number of syringe units you draw depends entirely on the vial concentration — not on which drug it is.

TL;DR — key takeaways

• Different scales. 2.4 mg is the top maintenance dose for semaglutide (Wegovy); tirzepatide goes up to 15 mg. A 2.4 mg dose is not "weak" — the two molecules simply use different number ranges.
• Same titration rhythm. Both labels increase the dose no sooner than every 4 weeks to let gastrointestinal side effects settle.
• Units follow concentration. Whether you draw 5, 20, or 60 units depends on the mg/mL strength of your vial, which is what a reconstitution or units calculator works out for you.
• Mechanism differs. Semaglutide is a single GLP-1 receptor agonist; tirzepatide is a dual GIP/GLP-1 receptor agonist.

Why the two dose scales look so different

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist. It mimics the GLP-1 hormone to promote glucose-dependent insulin release, slow gastric emptying, and reduce appetite. Tirzepatide is a dual agonist: it activates both the GLP-1 receptor and the glucose-dependent insulinotropic polypeptide (GIP) receptor. Because the two drugs bind different receptor sets with different potencies, their effective milligram ranges are not aligned — you cannot assume "1 mg of one equals 1 mg of the other."

Both share an elimination half-life of roughly five days, which is why each is dosed once weekly and reaches steady state after about four to five weeks — the same window over which the dose is being stepped up.

That slow build matters for tolerability. The appetite and gastric-emptying effects that drive weight loss are also what cause early nausea, so both labels deliberately start well below the therapeutic dose and hold each rung for a full four weeks before climbing. Rushing the staircase is the single most common reason people abandon either drug, which is why the schedule — not just the final number — is part of the dose.

Side-by-side: dosing at a glance

Figures above reflect the FDA-approved Wegovy and Zepbound labels for weight management. Compounded vials are drawn manually and require you to calculate the draw volume yourself; prescribed protocols may differ, so follow your prescriber's instructions.

The titration timeline, visualised

Both drugs follow the same staircase shape — hold each rung for at least four weeks — but on different vertical scales.

How to turn any dose into syringe units

This is where most people get stuck. The milligram dose on the label is not what you read on the syringe — you read units, and a U-100 insulin syringe has 100 units per 1 mL. So the conversion is always: 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

Common weekly doses for each drug, shown as units on a U-100 syringe at two typical compounded concentrations. Always confirm against your own vial label.

Notice the gap at 10 mg / 5 mg/mL: that dose would need 2 mL, more than a standard 1 mL syringe holds, so a higher-concentration vial is used for larger tirzepatide doses. If your draw exceeds 1 mL, ask your pharmacy about a stronger vial.

How this is calculated

Every figure here uses two facts only: a U-100 syringe holds 100 units per mL, and concentration is dose-per-volume. There is no drug-specific magic constant — the arithmetic is identical for semaglutide, tirzepatide, or any other vialled peptide. The calculators on this site automate exactly this, and let you sanity-check the result against the chart above. None of this is medical advice; it is the maths behind a dose your prescriber has set.

Frequently asked questions