Tirzepatide vs Dulaglutide Dosing Compared

Last updated: June 2026

Tirzepatide and dulaglutide are both once-weekly subcutaneous injections, but they sit on completely different dose ladders: tirzepatide climbs 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg per week, while dulaglutide climbs 0.75 → 1.5 → 3 → 4.5 mg per week. The milligram numbers are not comparable across the two drugs, and only one of them — compounded tirzepatide drawn from a vial — ever requires you to work out syringe units, because dulaglutide ships only as a fixed-dose pen.

Drawing compounded tirzepatide from a vial? Convert any weekly dose to exact mL and U-100 syringe units in seconds.

Tirzepatide calculator →

TL;DR — key takeaways

Different ladders. Tirzepatide tops out at 15 mg/week; dulaglutide tops out at 4.5 mg/week. A bigger number on one label does not mean a bigger effect than the other — the molecules use different scales.
Different mechanism. Tirzepatide is a dual GIP/GLP-1 receptor agonist; dulaglutide is a single GLP-1 receptor agonist.
Same 4-week rhythm. Both labels hold each dose for at least 4 weeks before stepping up, to let gastrointestinal side effects settle.
Only tirzepatide needs unit maths. Dulaglutide is a fixed-dose auto-injector pen — there is nothing to draw. Tirzepatide also comes as a pen, but compounded tirzepatide vials are drawn by hand, and that is where a units calculation matters.

Why the two dose scales look so different

Dulaglutide (Trulicity) is a glucagon-like peptide-1 (GLP-1) receptor agonist: it mimics the GLP-1 hormone to boost glucose-dependent insulin release, slow gastric emptying, and curb appetite. Tirzepatide (Mounjaro) is a dual agonist — it activates both the GLP-1 receptor and the glucose-dependent insulinotropic polypeptide (GIP) receptor. Because the two molecules bind different receptor sets with different potencies, their effective milligram ranges are not aligned. You cannot assume that 1.5 mg of dulaglutide and 1.5 mg of tirzepatide do anything like the same thing.

Both drugs have 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. In the head-to-head SURPASS J-mono trial, tirzepatide produced larger reductions in HbA1c and body weight than dulaglutide, but it was also titrated to much higher milligram doses, which is part of why the raw numbers cannot be compared rung-for-rung.

Side-by-side: dosing at a glance

Property	Tirzepatide	Dulaglutide
Brand (diabetes)	Mounjaro	Trulicity
Class	GIP + GLP-1 dual agonist	GLP-1 receptor agonist
Starting dose	2.5 mg / week	0.75 mg / week
Min step interval	4 weeks	4 weeks
Maximum dose	15 mg / week	4.5 mg / week
Dose ladder (mg)	2.5, 5, 7.5, 10, 12.5, 15	0.75, 1.5, 3, 4.5
Delivery	Pen or vial (incl. compounded)	Fixed-dose pen only
Approx. half-life	~5 days	~5 days

Figures reflect the FDA-approved Mounjaro and Trulicity labels for type 2 diabetes. Dulaglutide is not FDA-approved for weight management on its own; tirzepatide is approved for weight management under the brand Zepbound. Follow your prescriber's instructions, which may differ from the label.

The titration ladders, visualised

Both drugs follow the same staircase shape — hold each rung at least four weeks — but on very different vertical scales. Notice how few rungs dulaglutide has, and how much higher tirzepatide climbs.

Why only tirzepatide involves syringe units

This is the practical difference that trips people up. Dulaglutide is supplied only as a single-dose, pre-filled auto-injector pen holding a fixed 0.5 mL of drug; you press it against the skin and it delivers the whole fixed dose — there is no draw, no syringe, and no units to read. Tirzepatide is also sold as a pen, but it additionally comes as a single-dose vial, and compounded tirzepatide is frequently dispensed in multi-dose vials that you draw by hand with a U-100 insulin syringe. That is the only scenario in this comparison where unit maths applies.

When you do draw from a vial, the milligram dose on the label is not what you read on the barrel — you read units, and a U-100 insulin syringe has 100 units per 1 mL. The conversion is always the same: find the concentration (mg/mL), divide your dose by it to get mL, then multiply by 100 to get units.

Worked example 1 — tirzepatide start dose

You have a compounded vial at 10 mg/mL and your prescribed dose is 2.5 mg/week.

2.5 mg ÷ 10 mg/mL = 0.25 mL. 0.25 mL × 100 units/mL = 25 units.

Draw 25 units on a U-100 syringe.

Worked example 2 — tirzepatide step-up

Same 10 mg/mL vial, now stepping up to 5 mg/week after four weeks.

5 mg ÷ 10 mg/mL = 0.5 mL. 0.5 mL × 100 = 50 units.

Draw 50 units — exactly half of a 1 mL syringe.

Worked example 3 — reconstituting a powder vial

A 30 mg tirzepatide powder vial reconstituted with 1.5 mL bacteriostatic water gives 30 ÷ 1.5 = 20 mg/mL.

A 7.5 mg dose: 7.5 ÷ 20 = 0.375 mL × 100 = 37.5 units.

Draw to the 37 to 38 unit mark on a U-100 syringe.

Worked example 4 — dulaglutide has no draw

A dulaglutide 4.5 mg pen delivers a fixed 0.5 mL automatically. There is no concentration to look up and no units to read — you cannot "draw 4.5 mg" because the pen is sealed and pre-measured.

Units calculation: not applicable — fixed-dose device.

Tirzepatide dose-to-units reference chart

Common weekly tirzepatide doses as units on a U-100 syringe, at two typical compounded concentrations. This chart applies to tirzepatide vials only — dulaglutide is not drawn. Always confirm against your own vial label.

Tirzepatide dose	At 10 mg/mL	At 20 mg/mL
2.5 mg (start)	25 units	12.5 units
5 mg	50 units	25 units
7.5 mg	75 units	37.5 units
10 mg	100 units	50 units
12.5 mg	— (over 1 mL)	62.5 units
15 mg (max)	— (over 1 mL)	75 units

Notice that 12.5 mg and 15 mg need more than 1 mL at 10 mg/mL, so higher doses use a stronger vial. If your draw exceeds 1 mL, ask your pharmacy about a more concentrated vial rather than splitting the dose across two injections.

How this is calculated

Every tirzepatide figure here uses two facts only: a U-100 syringe holds 100 units per mL, and concentration is dose divided by volume. There is no drug-specific constant — the same arithmetic applies to any vialled peptide. Dulaglutide appears in the comparison for context, but it is intentionally absent from the unit chart because it is a fixed-dose pen with nothing to draw. The calculators on this site automate this arithmetic 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 already set.

Frequently asked questions

Is tirzepatide just a stronger dulaglutide?

No. Tirzepatide activates two receptors (GIP and GLP-1) while dulaglutide activates one (GLP-1). They are different molecules on different milligram scales, so a higher number on the tirzepatide label does not mean it is a higher "dose" of the same thing.

Why does dulaglutide stop at 4.5 mg but tirzepatide goes to 15 mg?

Each drug has its own approved dose range set by its clinical trials. 4.5 mg is the maximum approved dulaglutide dose, and 15 mg is the maximum approved tirzepatide dose. Comparing the raw milligram numbers across the two drugs is not meaningful.

How many units do I draw for dulaglutide?

None — dulaglutide comes only as a fixed-dose pre-filled pen that injects a set 0.5 mL automatically. There is no vial to draw from and no units to read. Unit calculations only apply to tirzepatide drawn from a vial.

Can I switch from dulaglutide to tirzepatide at the same dose?

No. The two ladders do not line up, so a prescriber starts tirzepatide at its own 2.5 mg starting dose and titrates from there, regardless of your previous dulaglutide dose. Do not map one dose onto the other yourself.

Sources

This guide is for general educational purposes only and does not constitute medical advice. Always follow your prescriber’s specific instructions and consult a qualified clinician before changing any protocol.