Tirzepatide Dosage Chart: Every Dose Conversion in One Place

Introduction

Tirzepatide has six approved dose strengths: 2.5, 5, 7.5, 10, 12.5, and 15 mg once weekly. That is twice as many titration steps as semaglutide, which makes the chart longer and the math more important. The branded Zepbound® and Mounjaro® pens dial directly to milligrams. Compounded tirzepatide is supplied in vials at concentrations that vary by pharmacy, and the dose has to be drawn into a U-100 insulin syringe in units.

This guide walks every dose strength across the three most common compounded concentrations (5 mg/mL, 10 mg/mL, 20 mg/mL) and the branded pen. The titration schedule comes from the FDA labels and from the SURMOUNT-1 trial protocol (Jastreboff et al. 2022 NEJM).

At TrimRx, we believe that understanding your options is the first step toward a more manageable health journey. You can take the free assessment quiz if you’re ready to see whether a personalized program is a fit for you.

What Is the Standard Tirzepatide Titration Schedule?

The standard schedule starts at 2.5 mg once weekly for four weeks. This is a non-therapeutic starting dose meant only to introduce the drug. Patients then move to 5 mg, the first therapeutic dose, and step up every 4 weeks to 7.5, 10, 12.5, and 15 mg. The maintenance dose is whatever step the patient tolerates and gets results from. Some patients stop at 7.5 mg. Others need the full 15 mg.

Quick Answer: Tirzepatide titration moves every 4 weeks: 2.5, 5, 7.5, 10, 12.5, 15 mg weekly

The SURMOUNT-1 protocol used this exact schedule, with a 20-week titration to reach 15 mg and 52 weeks of maintenance. The SURPASS program for type 2 diabetes used the same schedule but stopped at 5, 10, or 15 mg depending on the arm.

The reason for six steps instead of semaglutide’s five is that tirzepatide has higher rates of GI side effects at the top doses, and a slower climb keeps dropout rates down. SURMOUNT-1 had a 7% GI-related discontinuation rate in the 15 mg arm, compared with 2.6% in placebo.

How Do Milligrams Convert to Units on a U-100 Syringe?

A U-100 syringe is calibrated so 100 units equals 1 mL. To find the unit count for a tirzepatide dose, multiply the dose in mg by 100, then divide by the concentration in mg/mL. At a 10 mg/mL compounded concentration, the 5 mg dose is (5 x 100) / 10 = 50 units. At 20 mg/mL the same 5 mg dose is 25 units.

The volume in mL is dose (mg) divided by concentration (mg/mL). A 10 mg dose at 10 mg/mL is exactly 1.0 mL, which is the entire capacity of a standard 1 mL insulin syringe.

This matters because at the top doses, a 5 mg/mL concentration produces volumes that do not fit in a single syringe. 15 mg at 5 mg/mL is 3 mL. That cannot be drawn or injected in one shot. Higher concentrations are required for higher doses.

What Does the Chart Look Like at 10 mg/mL?

A 10 mg/mL compounded concentration is the most common starting concentration for tirzepatide. It keeps the unit numbers easy to read across the low and middle dose steps.

At 10 mg/mL:

• 2.5 mg = 25 units = 0.25 mL
• 5 mg = 50 units = 0.5 mL
• 7.5 mg = 75 units = 0.75 mL
• 10 mg = 100 units = 1.0 mL
• 12.5 mg = 125 units = 1.25 mL (does not fit a 1 mL syringe)
• 15 mg = 150 units = 1.5 mL (does not fit a 1 mL syringe)

At doses above 10 mg, a 10 mg/mL vial requires either a 2 mL syringe or a higher concentration. Most pharmacies switch patients to 20 mg/mL once they cross the 10 mg dose step.

What Does the Chart Look Like at 20 mg/mL?

A 20 mg/mL concentration is used for mid-to-high doses. It cuts the injection volume in half and keeps everything inside a single 1 mL syringe.

At 20 mg/mL:

• 2.5 mg = 12.5 units = 0.125 mL
• 5 mg = 25 units = 0.25 mL
• 7.5 mg = 37.5 units = 0.375 mL
• 10 mg = 50 units = 0.5 mL
• 12.5 mg = 62.5 units = 0.625 mL
• 15 mg = 75 units = 0.75 mL

The trade-off at 20 mg/mL is that the syringe has to be read at half-unit precision for the 2.5 mg and 7.5 mg steps. A 0.3 mL U-100 syringe with finer markings makes this easier than a 1 mL syringe.

What Does the Chart Look Like at 5 mg/mL?

A 5 mg/mL concentration is mostly used during the starting weeks because the unit numbers at 2.5 mg and 5 mg are large enough to read clearly. It is not practical above 7.5 mg.

At 5 mg/mL:

• 2.5 mg = 50 units = 0.5 mL
• 5 mg = 100 units = 1.0 mL
• 7.5 mg = 150 units = 1.5 mL (does not fit a 1 mL syringe)

If your starting kit is at 5 mg/mL, expect the pharmacy to switch you to a higher concentration when you move to 7.5 mg.

Key Takeaway: SURMOUNT-1 produced 20.9% mean weight loss at 72 weeks with 15 mg weekly

What Does the Chart Look Like for Zepbound and Mounjaro Pens?

Zepbound and Mounjaro are prefilled single-dose pens. Each pen contains exactly one weekly dose at one of the six strengths. There is no dialing, no drawing, and no unit conversion. The patient pulls the cap, presses the pen against the injection site, and holds for 10 seconds.

Both pens deliver a 0.5 mL injection volume regardless of strength. The drug concentration changes with the strength so that the same 0.5 mL volume contains 2.5, 5, 7.5, 10, 12.5, or 15 mg respectively.

The branded pens are mechanically incompatible with dose splitting. Patients sometimes ask if they can extract drug from a 15 mg pen to make two 7.5 mg doses. This is not possible without breaking the device, and Lilly does not endorse it.

What Dose Did SURMOUNT-1 Actually Use, and What Weight Loss Did It Produce?

The SURMOUNT-1 trial (Jastreboff et al. 2022 NEJM) tested three maintenance doses against placebo over 72 weeks in 2,539 adults with obesity. Mean weight loss was 15.0% at 5 mg, 19.5% at 10 mg, and 20.9% at 15 mg, compared with 3.1% in placebo. At 15 mg, 57% of participants lost at least 20% of body weight.

SURMOUNT-OSA (Malhotra et al. 2024 NEJM) tested tirzepatide for obstructive sleep apnea and led to FDA approval for OSA in December 2024 at 10 and 15 mg.

The SURPASS program tested tirzepatide for type 2 diabetes. SURPASS-2 (Frias et al. 2021 NEJM) compared 5, 10, and 15 mg tirzepatide to 1 mg semaglutide and produced superior A1C reductions at every dose, including the lowest 5 mg arm.

What If I Cannot Tolerate the Next STEP?

The FDA label allows a 4-week extension at any titration step “based on tolerability.” Patients who hit intolerable nausea at 10 mg often hold at 10 mg for 8 weeks before retrying 12.5 mg, or stay at 10 mg permanently if they are losing weight at an acceptable rate.

Maintenance does not have to be 15 mg. The SURMOUNT-1 5 mg arm still produced 15% weight loss, which is comparable to the 14.9% in STEP 1 with 2.4 mg semaglutide. Stopping at 10 mg is a reasonable target for patients who have hit their goal weight or who experience dose-limiting side effects.

Going backwards is also allowed. A patient at 15 mg with persistent vomiting can drop to 12.5 mg or 10 mg and continue at the lower dose indefinitely.

How Does TrimRx Prescribe Tirzepatide?

TrimRx prescribes compounded tirzepatide through licensed U.S. providers. The starting kit is usually at 10 mg/mL in a 2 mL vial, with a switch to 20 mg/mL once the dose passes 10 mg weekly. Each shipment includes a dosing label that shows the unit conversion for the specific vial concentration.

A free assessment quiz checks eligibility and starting dose. The personalized treatment plan accounts for prior GLP-1 history, BMI, comorbidities, and tolerability.

Bottom line: Compounded concentrations vary widely (5, 10, 20, even 40 mg/mL), so recalculate every time the vial changes

FAQ

Why Does Tirzepatide Have a 2.5 Mg Starting Dose If It Does Not Produce Weight Loss?

The 2.5 mg dose is meant to acclimate the gut to GLP-1 and GIP receptor activity. SURMOUNT-1 produced about 4% weight loss in the first 4 weeks at this dose, but the FDA labels it as “non-therapeutic” because the long-term weight loss curve only begins at 5 mg.

Is the 1.7 Mg Semaglutide STEP Roughly Equal to the 5 Mg Tirzepatide STEP?

No. Tirzepatide is more potent per milligram. SURPASS-2 head-to-head data show 5 mg tirzepatide produces greater A1C and weight loss than 1 mg semaglutide. There is no direct mg-to-mg equivalence between the two drugs.

What If My Vial Concentration Changes Between Shipments?

Stop and recalculate before the first injection from the new vial. Pharmacies change concentrations as patients titrate up. Use the formula dose (mg) x 100 / concentration (mg/mL) = units.

Can I Round My Unit Count?

Round to the nearest mark on your syringe. A 1 mL U-100 syringe has marks every 2 units. A 0.3 mL or 0.5 mL syringe has marks every 1 unit. Rounding within 1 to 2 units of the target dose is clinically insignificant.

How Many Doses Does a 2 mL Vial Contain?

A 2 mL vial at 10 mg/mL contains 20 mg of drug. At a 5 mg weekly dose that is 4 doses. At 10 mg weekly it is 2 doses. Pharmacies usually ship a vial size that covers a 4-week supply.

Can I Split a Zepbound Pen?

No. Zepbound pens are single-dose and the activation mechanism cannot be reset. Splitting is mechanically impossible without breaking the device.

Does Tirzepatide Need Refrigeration?

Branded pens require refrigeration at 36 to 46 F until use, and tolerate room temperature for up to 21 days. Compounded vials follow the same rule. Once a vial is opened, refrigerate it and use within 28 days unless the pharmacy specifies otherwise.

Disclaimer: This content is for informational purposes only and does not constitute medical advice. It is not intended to diagnose, treat, cure, or prevent any disease or condition. Individual results may vary. Always consult a qualified healthcare professional before starting any weight loss program or medication.