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Zepbound units to mL to mg calculator (U-100)

Zepbound (tirzepatide) comes as a single-dose pen, a multi-dose KwikPen, and vials you draw up yourself, which since early 2026 come in single-dose and multi-dose versions. Units only matter for the vials: your prescription is in mg, a single-dose vial holds 0.5 mL, a multi-dose vial gives four 0.6 mL doses, and insulin syringes read in units. This calculator converts between all three in seconds.

This page is general information and arithmetic only, not medical or dosing advice. Always follow your prescriber and the official product information.

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Pen or vial strength

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Units (U-100)

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This calculator shows general arithmetic only, not dosing advice. Always follow your prescriber and official instructions.

Quick facts

U-100: 100 units = 1 mL (so 1 unit = 0.01 mL)
Single-dose pen or vial (US): 0.5 mL = 50 units
Multi-dose vial or KwikPen dose (US): 0.6 mL = 60 units
One single-dose pen or vial = one weekly dose (the multi-dose vial and KwikPen each hold 4)
Strengths: 2.5, 5, 7.5, 10, 12.5, 15 mg per dose in every format; single-dose formats put that in 0.5 mL, multi-dose formats in 0.6 mL

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Zepbound quick facts

Dose volume, single-dose pen and vial (US): 0.5 mL, the same at every strength (the multi-dose vial and KwikPen deliver 0.6 mL per dose)
Formats: single-dose auto-injector pen, single-dose vial, multi-dose vial (4 doses), or multi-dose KwikPen (4 doses); the single-dose vials and the KwikPen are sold through LillyDirect self-pay
Available strengths: 2.5, 5, 7.5, 10, 12.5, 15 mg per dose in every format (in 0.5 mL for single-dose, 0.6 mL for multi-dose)
A 28-day supply: 4 single-dose pens or vials, 1 multi-dose vial, or 1 KwikPen (one injection a week)

Pens vs vials: where units come in

If you use the Zepbound pen, you never see a unit. It's a fixed-dose auto-injector: press it against your skin, it delivers the full 0.5 mL, done. No dial, no syringe, no math. The multi-dose KwikPen is the same idea in a different shape: four fixed 0.6 mL doses, a knob you turn to the stop, still no syringe.

The vials are different. There are two on the label: the original single-dose vial (one 0.5 mL dose) and, since the February 2026 label update, a multi-dose vial holding four 0.6 mL doses. LillyDirect's self-pay prices cover the single-dose vial and the KwikPen. With either vial you draw each dose up yourself. The FDA prescribing information says to use a syringe appropriate for the dose, for example a 1 mL syringe that can measure a 0.5 mL or 0.6 mL dose. In practice, many people end up with U-100 insulin syringes, and those are marked in units rather than mL. So you're holding a prescription in mg, a vial labeled in mg, and a syringe that reads in units. That's the exact gap this calculator fills.

Two numbers worth memorizing: a full dose from a single-dose vial is always 50 units (0.5 mL) on a U-100 syringe, and a full dose from a multi-dose vial is always 60 units (0.6 mL), whatever the strength. Within each format, the difference between strengths is concentration, not volume. It also means the two vial types are not interchangeable in the math: a 5 mg single-dose vial is 10 mg per mL, while a multi-dose vial with 5 mg doses is about 8.3 mg per mL. Match the calculator's device option to the vial in your hand.

How the calculator works

Units are a way of measuring volume on a U-100 syringe (100 units = 1 mL). Vial strength changes the concentration (mg per mL), so the same number of units contains a different amount of medicine depending on which strength you have.

The calculator uses three values: the strength in mg per dose, the dose volume for your format (0.5 mL for the single-dose pen and vial, 0.6 mL for the multi-dose vial and KwikPen), and the U-100 definition (100 units = 1 mL). Pick the device option that matches your container; the formulas below use the single-dose 0.5 mL as the example.

mg per mL = strength ÷ dose volume (0.5 for single-dose, 0.6 for multi-dose)
From units: mL = units ÷ 100, then mg = mL × mg per mL
From mL: units = mL × 100, then mg = mL × mg per mL
From mg: mL = mg ÷ mg per mL, then units = mL × 100

Single-dose shortcut (because 0.5 mL = 50 units):

mg = (units ÷ 50) × vial strength

For example, 25 units from a 5 mg vial: (25 ÷ 50) × 5 = 2.5 mg

Multi-dose shortcut (because 0.6 mL = 60 units):

mg = (units ÷ 60) × strength per dose

For example, 30 units from a multi-dose vial with 5 mg doses: (30 ÷ 60) × 5 = 2.5 mg

Common conversions

This table shows the basic relationship between U-100 units and mL. It's the same for every strength:

U-100 units to mL conversion (100 units = 1 mL)
Units (U-100)	mL
5	0.05
10	0.10
20	0.20
25	0.25
30	0.30
40	0.40
50	0.50

Master conversion table (US single-dose pen and vial, 0.5 mL)

Read across from your syringe units to see roughly how many mg each single-dose strength delivers. The table uses the same formulas as the calculator above, and 50 units is the full dose for every single-dose strength. This table does not apply to the multi-dose vial or KwikPen: their full dose is 60 units and the concentrations are lower, so use the calculator's multi-dose option instead.

US Zepbound conversion: units to mL and mg delivered (approx) for all single-dose strengths
Units	mL	2.5 mg	5 mg	7.5 mg	10 mg	12.5 mg	15 mg
5	0.05	0.25	0.50	0.75	1.00	1.25	1.50
10	0.10	0.50	1.00	1.50	2.00	2.50	3.00
15	0.15	0.75	1.50	2.25	3.00	3.75	4.50
20	0.20	1.00	2.00	3.00	4.00	5.00	6.00
25	0.25	1.25	2.50	3.75	5.00	6.25	7.50
30	0.30	1.50	3.00	4.50	6.00	7.50	9.00
35	0.35	1.75	3.50	5.25	7.00	8.75	10.50
40	0.40	2.00	4.00	6.00	8.00	10.00	12.00
45	0.45	2.25	4.50	6.75	9.00	11.25	13.50
50	0.50	2.50	5.00	7.50	10.00	12.50	15.00

Target dose look-up (by strength)

Pick a target mg, then read across to find the approximate units for each single-dose vial strength. Values are rounded to the nearest half unit. A dash means the target is more than one full vial of that strength.

Be clear about what this table is. Zepbound single-dose vials are labeled for one full 0.5 mL dose, injected once and then thrown away. Drawing a smaller, partial dose (splitting or "microdosing" a vial) is off-label: the FDA label does not support it, and anyone doing it is outside the approved instructions and taking that on themselves. The table is arithmetic, not an endorsement. Talk to your prescriber before changing any dose.

Target mg to units by single-dose vial strength (US, 0.5 mL)
Single-dose vial	0.5 mg	1 mg	2.5 mg	3 mg	5 mg
2.5 mg	10 u	20 u	50 u	–	–
5 mg	5 u	10 u	25 u	30 u	50 u
7.5 mg	3.5 u	6.5 u	16.5 u	20 u	33.5 u
10 mg	2.5 u	5 u	12.5 u	15 u	25 u
12.5 mg	2 u	4 u	10 u	12 u	20 u
15 mg	1.5 u	3.5 u	8.5 u	10 u	16.5 u

What Zepbound costs in the US

The vials exist because of price. LillyDirect's self-pay program sells Zepbound directly to patients without insurance coverage, and single-dose vials are a core part of that offer. As of July 2026:

The list price is around $1,086 a month, but almost nobody pays that.
LillyDirect self-pay is $299 a month for 2.5 mg, $399 for 5 mg, and $449 for 7.5 mg and up, for a 28-day supply of the single-dose vial or KwikPen. The $449 price on the higher strengths depends on refilling within 45 days of your last fill. Miss the window and the regular self-pay rates apply: $499 for 7.5 mg and $699 for 10 mg, 12.5 mg, and 15 mg.
With commercial insurance, the Zepbound savings card can bring the cost down to as little as $25 a month. Savings cards are not available to people on Medicare, Medicaid, or other government programs.
From July 1, 2026, the Medicare GLP-1 Bridge gives eligible Part D enrollees Zepbound for a copay of no more than $50 a month. It covers the multi-dose KwikPen only, not the single-dose pen or either vial format, and runs through December 31, 2027.

Prices have changed more than once this year, so check lilly.com for the current terms before you rely on any figure here.

Why real-world use can differ

The tables and calculator show pure arithmetic based on labeled strengths and volumes. In real-world use, the official instructions matter more. If the math and the instructions ever conflict, the instructions win.

The auto-injector pen and the original vial are single-dose. The prescribing information says to use each one once and discard it, even if a little liquid appears to remain. The multi-dose vial and KwikPen hold four doses each; you throw them away 30 days after first use or after the fourth dose, whichever comes first.
The label directs you to inject the full labeled dose: 0.5 mL from single-dose containers, 0.6 mL per dose from multi-dose ones. You'll see people online discussing splitting vials into smaller doses; the arithmetic on this page can describe that, but it is off-label and the label doesn't support it. That's a conversation for your prescriber.
Missed dose rule: take it as soon as possible within 4 days (96 hours). Past that, skip it and take the next dose on your usual day.
Storage: keep Zepbound refrigerated at 36°F to 46°F. A single-dose pen or vial can sit at room temperature (up to 86°F) for a maximum of 21 days. The multi-dose vial and KwikPen get up to 30 days at room temperature, and are discarded 30 days after first use even if medicine remains.

Log your weekly Zepbound dose in units, mL, or mg and see your weight trend alongside it.

FAQs

What is a U-100 insulin syringe?▾

A U-100 syringe shows volume in 'units' where 100 units equals 1.00 mL, so 1 unit is 0.01 mL. It is a fine-grained volume scale designed for insulin, and it is the syringe type most people reach for when drawing a dose from a Zepbound vial. On a U-100 scale, the full 0.5 mL single-dose vial is 50 units, and one 0.6 mL dose from the multi-dose vial is 60 units.

How many units is one full Zepbound dose?▾

It depends on the container. One full dose from a US Zepbound single-dose pen or vial is 0.5 mL, which is 50 units on a U-100 syringe. One full dose from the multi-dose vial or KwikPen is 0.6 mL, which is 60 units. Within each format the volume is the same at every strength, because each strength packs its milligrams into the same fixed volume.

Do Zepbound pens use units?▾

No. The Zepbound single-dose pen is a fixed-dose auto-injector: you press it against your skin and it delivers the full 0.5 mL automatically. The multi-dose KwikPen holds four fixed 0.6 mL doses; you turn the knob to the stop, so there is nothing to measure there either. Units only come into play when you draw a dose from a vial with a syringe, whether that is the full 0.5 mL from a single-dose vial or a 0.6 mL dose from the multi-dose vial.

Does vial strength change how many units I need for the same mg?▾

Yes. Stronger vials pack more mg into the same volume, so you need fewer units (less volume) to reach the same mg. For example, 2.5 mg is 25 units from a 5 mg single-dose vial but only 12.5 units from a 10 mg single-dose vial. The multi-dose vial is less concentrated again, because each dose sits in 0.6 mL rather than 0.5 mL: from a multi-dose vial with 5 mg doses, 2.5 mg is 30 units. Always match the calculator's device option to the vial in your hand.

Is Zepbound the same as Mounjaro?▾

Both contain the same active ingredient, tirzepatide. In the US, Zepbound is FDA-approved for chronic weight management and obstructive sleep apnea, while Mounjaro is approved for type 2 diabetes. In the UK, the weight loss brand is Mounjaro, sold as a multi-dose KwikPen that delivers 0.6 mL per dose, the same per-dose volume as the US multi-dose formats but not the 0.5 mL US single-dose formats. That is why this calculator has separate device options with different math.

Can I get more than one dose from a vial?▾

From a single-dose vial, no. It holds one 0.5 mL dose, and the FDA prescribing information says to discard it after use, even if some liquid appears to remain. The multi-dose vial is different: it holds 2.4 mL, enough for four 0.6 mL doses, and you throw it away 30 days after first use or after the fourth dose, whichever comes first.

Is this calculator medical advice?▾

No. This calculator shows general arithmetic based on labeled strengths and U-100 syringe markings. It is not dosing advice. Always follow your prescriber and the official product instructions.

Sources

Zepbound Prescribing Information (Lilly USPI)

Lilly, Zepbound US Prescribing Information covers the 0.5 mL and 0.6 mL dose volumes, the single-dose and multi-dose presentations, syringe guidance, missed-dose rule, and storage.

FDA approval label for Zepbound

FDA, Zepbound label (NDA 217806) is the original approval label on the FDA's drug database.

DailyMed entry for Zepbound

DailyMed, Zepbound (tirzepatide) injection lists the single-dose pen and vial presentations (0.5 mL each) plus the multi-dose vial and KwikPen (four 0.6 mL doses each).

LillyDirect self-pay terms

Lilly, Zepbound self-pay full terms and conditions sets out vial pricing and the 45-day refill window.

Zepbound savings card

Lilly, Zepbound savings and support covers the commercial-insurance savings card and its government-program exclusions.

Medicare GLP-1 Bridge

CMS, Medicare GLP-1 Bridge is the official page for the $50 copay program that runs July 1, 2026 to December 31, 2027 and covers the Zepbound KwikPen. Medicare's fact sheet (PDF) explains eligibility and that the $50 copay does not count toward the Part D out-of-pocket cap.

List price reference

GoodRx, Zepbound prices tracks the list price and pharmacy cash prices.

Last reviewed: July 2026