Dose calculator · tirzepatide

Tirzepatide Dosage Calculator: mg to Units (U⁠-⁠100 Syringe)

To turn a tirzepatide dose into units, divide the dose in mg by the strength on your vial (mg per mL). That gives you mL. Multiply by 100 to get units on a U-100 insulin syringe. For example, 5 mg from a 10 mg/mL vial is 0.5 mL, or 50 units on a U-100 insulin syringe. A U-40 or other syringe would give a different draw. Single-dose and multi-dose vials have different strengths, so check which one you have.

Last updated September 30, 2026

Sold as: Mounjaro, Zepbound
Label doses: 2.5 mg to 15 mg

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Tirzepatide calculator

U-100 syringe: 100 units = 1 mL

Step 1 of 425%

What kind of vial do you have?

Powder: you add liquid to it before the first dose.Liquid: the label shows a strength in mg/mL.

The math in plain language

The formula

Units to draw = dose (mg) ÷ vial strength (mg/mL) × 100. That works on any U-100 insulin syringe, where 100 units = 1 mL.

Example for tirzepatide:5 mg from a 10 mg/mL vial → 5 ÷ 10 × 100 = 50 units (0.50 mL).

Mixing a powder vial? Strength = mg in the vial ÷ mL of water added. 10 mg + 2 mL = 5 mg/mL. The vial label's strength is what decides the answer.

How to read your result

The result is the amount of liquid in units on a U-100 syringe. It is not a recommended dose. Syringe makers name the thin black line, the top of the plunger, or the plunger tip as the reference for the dose line. We read all three as the edge of the plunger closest to the needle. The same mg dose can be a different number of units in a different type of vial.

Check the label before you do the math. The units vs mL vs mg guide explains the three numbers, and the guide to reading a syringe explains the lines.

If your medicine came from a pharmacy vial

Compounded tirzepatide: what the FDA says

“Compounded” means a pharmacy made its own version instead of the brand-name product. If your tirzepatide came from a pharmacy in a vial, here is what matters most:

Throw the vial away 28 days after you first use it, even if its label says it lasts longer.
Use a new sterile needle and syringe for every dose.
The FDA has hundreds of reports of side effects and other problems with compounded versions, some involving doses higher than the label’s schedule.
The shortage is over. The FDA says pharmacies may no longer regularly make copies of the brand-name medicine.

The details from the FDA

The tirzepatide shortage was resolved in 2024. The FDA then gave compounders a wind-down period, when it held off on enforcing its rules against compounded (pharmacy-made) copies. That period ended February 18, 2025 for 503A pharmacies (standard compounding pharmacies) and March 19, 2025 for 503B outsourcing facilities (larger-scale compounders). The FDA says 503A pharmacies may not regularly compound a drug that is “essentially a copy” of one sold commercially. Adding vitamin B12 does not get around that rule when the strength is within 10%. The FDA also says 503B outsourcing facilities may not use tirzepatide as a raw drug ingredient (API), because it is not on the 503B bulks list or a shortage list. As of May 31, 2026, the FDA had 990 reports of side effects or other problems (adverse events) with compounded semaglutide and more than 730 with compounded tirzepatide.

Vial types on the label

These are the vials listed on the label, and their amounts are fixed. A single-dose vial gives 0.5 mL. A multi-dose vial holds 2.4 mL and gives 0.6 mL per dose.

Only the vial types on the label. The labels give amounts in mL. We turned those into units on a U-100 syringe, where 1 unit is 0.01 mL.
Strength	Single-dose vial	Multi-dose vial
2.5 mg	0.5 mL = 50 units 5.00 mg/mL	0.6 mL = 60 units 4.17 mg/mL; 2.4 mL holds 4 doses
5 mg	0.5 mL = 50 units 10.00 mg/mL	0.6 mL = 60 units 8.33 mg/mL; 2.4 mL holds 4 doses
7.5 mg	0.5 mL = 50 units 15.00 mg/mL	0.6 mL = 60 units 12.50 mg/mL; 2.4 mL holds 4 doses
10 mg	0.5 mL = 50 units 20.00 mg/mL	0.6 mL = 60 units 16.67 mg/mL; 2.4 mL holds 4 doses
12.5 mg	0.5 mL = 50 units 25.00 mg/mL	0.6 mL = 60 units 20.83 mg/mL; 2.4 mL holds 4 doses
15 mg	0.5 mL = 50 units 30.00 mg/mL	0.6 mL = 60 units 25.00 mg/mL; 2.4 mL holds 4 doses

Brand-name vs compounded: what is different about the vial?

The brand-name tirzepatide forms listed here are Mounjaro and Zepbound pens, Mounjaro and Zepbound single-dose and multi-dose vials, and Mounjaro and Zepbound KwikPens.

A brand-name Mounjaro or Zepbound single-dose vial holds one dose in 0.5 mL, so its label tells you the volume.

Compounded means a pharmacy made its own version instead of the brand-name product. Its strength is the mg/mL printed on that vial's label, so the units depend on your vial.

The FDA has received reports of problems with compounded tirzepatide, including doses higher than the label's schedule.

Reference table

Tirzepatide: mg to units

For other vial strengths, use the column for that strength (mg/mL). The vial types on the label are listed above.

Find the mg/mL on your vial label. Units are for a U-100 insulin syringe (1 unit is 0.01 mL). Always check the lines on your own syringe.
Dose	5 mg/mL	10 mg/mL	15 mg/mL	20 mg/mL	25 mg/mL	30 mg/mL
2.5 mg	50	25	16.7	12.5	10	8.3
5 mg	100	50	33.3	25	20	16.7
7.5 mg	—	75	50	37.5	30	25
10 mg	—	100	66.7	50	40	33.3
12.5 mg	—	—	83.3	62.5	50	41.7
15 mg	—	—	100	75	60	50
To measure a half unit, you need a syringe with ½-unit lines (see syringe sizes). Whether you can read an amount depends on the lines on your own syringe.

A dash (—) means the amount is more than a 1 mL syringe holds at this strength. The table shows exact units. Whether you can measure an amount depends on the lines on your own syringe. This table is only math, not dose instructions.

How the FDA labels step up the dose

The Mounjaro and Zepbound labels start at 2.5 mg. After at least 4 weeks on the current dose, the dose goes up by 2.5 mg at a time. This table just shows what the labels say. It does not tell you which dose to use.

For reference only. The product label and your prescriber decide the dose.
Step	Dose (mg)	What the label says
From the label
Starting dose	2.5	Once a week for 4 weeks, on the Mounjaro and Zepbound labels.
After at least 4 weeks	5	After at least 4 weeks at 2.5 mg.
Later increases	7.5	On the labels, the dose goes up by 2.5 mg at a time, after at least 4 weeks on the current dose.
Later increases	10	After at least 4 weeks at 7.5 mg.
Later increases	12.5	After at least 4 weeks at 10 mg.
Later increases	15	The highest weekly dose on the adult labels.

Key facts

Where to inject, what to do after a missed dose, and how to store it, as the label puts it.

Injection sites

The Mounjaro and Zepbound labels list the stomach area (abdomen) or thigh. The back of the upper arm is listed only when someone else gives the injection. Use a different spot each time you inject.

Missed dose

Mounjaro: If it has been 4 days (96 hours) or less, take the missed dose as soon as you can. If more than 4 days have passed, skip it.

Zepbound: If it has been 4 days (96 hours) or less, take the missed dose as soon as you can. If more than 4 days have passed, skip it.

Storage

Keep single-dose Mounjaro and Zepbound pens or vials in the fridge. They can be kept at or below 30 °C (86 °F) for a total of 21 days.

Throw away multi-dose vials and KwikPens after 30 days at room temperature, 30 days after first use, or 4 weekly doses, whichever comes first.

Common mistakes

The FDA has received reports of problems with compounded tirzepatide, including doses higher than the label's schedule.

Read the guide to common dosing mistakes

If you are not sure about the strength or the lines on your syringe, stop and check the label with your healthcare provider or pharmacist.

Common questions

How many units is 0.5 mL?

0.5 mL is 50 units on a U-100 insulin syringe. The type of vial on the label matters: the single-dose vial uses 0.5 mL, and the multi-dose vial uses 0.6 mL per dose.

Sources: Zepbound (tirzepatide) US Prescribing Information, Technical Data Sheet – Insulin Syringes

How many units is 0.6 mL?

0.6 mL is 60 units on a U-100 insulin syringe. The label gives the amount in mL. The units number comes from how a U-100 syringe works: 100 units fill 1 mL.

Sources: Mounjaro (tirzepatide) US Prescribing Information, Zepbound (tirzepatide) US Prescribing Information, Technical Data Sheet – Insulin Syringes

Why don’t all 5 mg vials have the same strength?

A single-dose vial holds the amount on its label in 0.5 mL. A multi-dose vial holds four 0.6 mL doses in 2.4 mL. So the strength (mg per mL) is different.

Sources: Mounjaro (tirzepatide) US Prescribing Information, Zepbound (tirzepatide) US Prescribing Information

Can I use the units for a single-dose vial with a multi-dose vial?

No. Use the amount and strength for the exact product in front of you. The labels list the 0.5 mL and 0.6 mL vials separately.

Sources: Mounjaro (tirzepatide) US Prescribing Information, Zepbound (tirzepatide) US Prescribing Information, Zepbound single-dose vial Instructions for Use

What do the instructions say about drawing a dose from a vial?

The Mounjaro and Zepbound instructions say to use a syringe that is right for the dose. The Zepbound single-dose vial instructions measure to the 0.5 mL line. The multi-dose vial instructions use the 0.6 mL line.

Sources: Mounjaro (tirzepatide) US Prescribing Information, Zepbound single-dose vial Instructions for Use, Zepbound full US labeling

Does this page recommend a tirzepatide dose?

This page does not recommend a tirzepatide dose; dosage is determined by the official product label and your healthcare provider.

Sources: Mounjaro (tirzepatide) US Prescribing Information, Zepbound (tirzepatide) US Prescribing Information

Other calculators, quick answers for common doses, the pens and vials on the label, and the how-to guides.

All guides

Double-check the math every time

It takes about 20 seconds. Have your prescription and your vial in front of you while you check it.

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Sources

The medical and device facts on this page come from these sources. Each entry shows the date we accessed it.

01 Mounjaro (tirzepatide) US Prescribing Information · Eli Lilly, 08/2026. Accessed 2026-09-28.
02 Zepbound (tirzepatide) US Prescribing Information · Eli Lilly, 08/2026. Accessed 2026-09-28.
03 Zepbound single-dose vial Instructions for Use · Eli Lilly, 04/2026. Accessed 2026-09-28.
04 Zepbound full US labeling · Eli Lilly, 08/2026. Accessed 2026-10-01.
05 Technical Data Sheet – Insulin Syringes · embecta, Rev B, 12/2025. Accessed 2026-09-28.
08 SafetyGlide Insulin Syringes quick reference guide · embecta. Accessed 2026-09-28.
09 ISO 8537:2016, sterile single-use insulin syringes · International Organization for Standardization, 2016. Accessed 2026-09-28.
10 FDA's concerns with unapproved GLP-1 drugs used for weight loss · U.S. Food and Drug Administration, 10/01/2026. Accessed 2026-10-01.
11 FDA clarifies policies for compounders as GLP-1 supply stabilizes · U.S. Food and Drug Administration, 04/01/2026. Accessed 2026-09-28.

Medically reviewed by Ashley Alexis, NDLast reviewed September 30, 2026How we review