2.5 mg on the labelEvery tirzepatide patient starts at 2.5 mg once weekly. For Zepbound, “the 2.5 mg dosage is for treatment initiation and is not approved as a maintenance dosage.”[1] Since August 2026 the Mounjaro label lets 2.5 mg continue for blood-sugar control.[2]
2.5 mg in each kind of vial
2.5 mg is 50 units in a single-dose vial, 60 units in a multi-dose vial, and between 8.3 and 100 units in other solutions.
| Vial or solution | Concentration | mL | Units (U-100) |
|---|---|---|---|
| Single-dose vial, 2.5 mg / 0.5 mL | 5 mg/mL | 0.5 | 50 |
| Multi-dose vial, 10 mg / 2.4 mL | 4.17 mg/mL | 0.6 | 60 |
| Single-dose pen or KwikPen | — | Fixed by the pen | Not measured |
| Other solution at 2.5 mg/mL | 2.5 mg/mL | 1 | 100 |
| Other solution at 10 mg/mL | 10 mg/mL | 0.25 | 25 |
| Other solution at 15 mg/mL | 15 mg/mL | 0.167 | 16.7 |
| Other solution at 20 mg/mL | 20 mg/mL | 0.125 | 12.5 |
| Other solution at 25 mg/mL | 25 mg/mL | 0.1 | 10 |
| Other solution at 30 mg/mL | 30 mg/mL | 0.083 | 8.3 |
The two approved vials hold the same 2.5 mg in different volumes. The single-dose vial has 0.5 mL and is used once; the multi-dose vial spreads four doses through 2.4 mL, so each dose is 0.6 mL.[1] The label says to use “a 1 mL syringe capable of measuring a 0.5 mL or 0.6 mL dose” and to “always use a new syringe and needle for each injection.”[1] It measures by the mL lines and never mentions units; 50 and 60 units are the same volumes read on a U-100 insulin syringe.[9]
A pen needs no reading at all: the autoinjector and the KwikPen deliver their fixed dose. See Zepbound pen vs vial and the Zepbound vial guide.
Why 2.5 mg can be 12.5 units or 100 units
The milligrams never change; the volume does. At 20 mg/mL, 2.5 mg is a small 0.125 mL draw (12.5 units). At 2.5 mg/mL it fills a whole 1 mL syringe (100 units). An FDA alert about compounded semaglutide described dosing errors from exactly this kind of “confusion between different units of measurement (e.g., milliliters, milligrams and ‘units’)”.[9] Before converting, confirm whether a label states a concentration (“10 mg/mL”) or a total (“10 mg/2.4 mL”). The full two-way chart is on tirzepatide units to mg.
2.5 mg from a powder vial mixed with water
No approved tirzepatide is a powder; this grid is arithmetic for compounded or unapproved powder, which the FDA does not review for quality.[10] A dash means more than a 1 mL syringe holds. Mixing math is explained on the bac water calculator, and compounded vial labels on compounded tirzepatide dosage.
| Vial | 0.5 mL | 1 mL | 1.5 mL | 2 mL | 2.5 mL | 3 mL | Doses |
|---|---|---|---|---|---|---|---|
| 5 mg | 25 | 50 | 75 | 100 | – | – | 2 |
| 10 mg | 12.5 | 25 | 37.5 | 50 | 62.5 | 75 | 4 |
| 15 mg | 8.3 | 16.7 | 25 | 33.3 | 41.7 | 50 | 6 |
| 20 mg | 6.3 | 12.5 | 18.8 | 25 | 31.3 | 37.5 | 8 |
| 30 mg | 4.2 | 8.3 | 12.5 | 16.7 | 20.8 | 25 | 12 |
| 40 mg | 3.1 | 6.3 | 9.4 | 12.5 | 15.6 | 18.8 | 16 |
| 60 mg | 2.1 | 4.2 | 6.3 | 8.3 | 10.4 | 12.5 | 24 |
What happens on 2.5 mg
2.5 mg lasts 4 weeks; after that the label moves everyone to 5 mg.[1] In SURMOUNT-1 all three dose groups began at 2.5 mg for those first 4 weeks, so no group stayed on it.[3] The label notes that “the majority of nausea, vomiting, and/or diarrhea events occurred during dose escalation and decreased over time.”[1] The 2.5 mg vial was one of the first two strengths Lilly sold as vials, in August 2024.[6] Self-pay today: $299 per 4-dose fill.[5] The dosage chart shows the whole schedule.
Zepbound dosage chart in units: every dose at a glance
Every Zepbound vial dose reads 50 units (single-dose) or 60 units (multi-dose); only solutions of other strengths change the reading.
| Dose | Single-dose vial | Multi-dose vial | 10 mg/mL | 20 mg/mL | Smallest syringe at 10 mg/mL |
|---|---|---|---|---|---|
| 2.5 mg | 50 | 60 | 25 | 12.5 | 0.3 mL (30-unit) |
| 5 mg | 50 | 60 | 50 | 25 | 0.5 mL (50-unit) |
| 7.5 mg | 50 | 60 | 75 | 37.5 | 1 mL (100-unit) |
| 10 mg | 50 | 60 | 100 | 50 | 1 mL (100-unit) |
| 12.5 mg | 50 | 60 | 125 | 62.5 | more than 1 mL |
| 15 mg | 50 | 60 | 150 | 75 | more than 1 mL |
How many units is 5 mg of tirzepatide?
5 mg = 50 units from a 5 mg single-dose vial (the whole 0.5 mL, 10 mg/mL) and 60 units from a 5 mg multi-dose vial (0.6 mL at 8.33 mg/mL). From a 10 mg/mL solution it is 50 units; from 20 mg/mL, 25 units.
5 mg is where every patient goes after the 4-week start, so it is the first dose people reach (week 5 at the earliest). It is the lowest of the three Zepbound maintenance doses for weight.[1] In SURMOUNT-1, people assigned to stay on 5 mg lost −15% of body weight on average over 72 weeks, and 30% lost a fifth or more.[3] Constipation was more common at 5 mg (17%) than at 15 mg (11%) in the label's pooled data.[1] In type 2 diabetes (SURPASS-2), 5 mg lowered HbA1c by 2.01 points.[4] Self-pay: $399 per 4-dose fill.[5]
How many units is 7.5 mg of tirzepatide?
7.5 mg = 50 units from a 7.5 mg single-dose vial (the whole 0.5 mL, 15 mg/mL) and 60 units from a 7.5 mg multi-dose vial (0.6 mL at 12.5 mg/mL). From a 10 mg/mL solution it is 75 units; from 20 mg/mL, 37.5 units.
7.5 mg is a step, not a destination, on the Zepbound label: it is not one of the listed maintenance doses for weight or sleep apnea, so people usually pass through it for at least 4 weeks on the way to 10 mg.[1] Mounjaro has no fixed maintenance list, so a person with type 2 diabetes may stay at 7.5 mg if it controls blood sugar.[2] SURMOUNT-1 had no 7.5 mg arm. The 7.5 mg vial arrived in February 2025, together with 10 mg, and these two were the first strengths sold at Lilly's lower on-time refill price.[7] Self-pay today: $449 per 4-dose fill with on-time refills (otherwise $499).[5]
How many units is 10 mg of tirzepatide?
10 mg = 50 units from a 10 mg single-dose vial (the whole 0.5 mL, 20 mg/mL) and 60 units from a 10 mg multi-dose vial (0.6 mL at 16.67 mg/mL). From a 10 mg/mL solution it is 100 units; from 20 mg/mL, 50 units.
10 mg is the only dose that is a listed Zepbound maintenance dose for both uses: weight (5, 10 or 15 mg) and obstructive sleep apnea (10 or 15 mg).[1] For children aged 10 and older on Mounjaro it is also the ceiling.[2] SURMOUNT-1 reported −19.5% average weight change at 10 mg, with 50.1% losing 20% or more.[3] Nausea peaked at this dose in the pooled label data (29%), and 6.3% stopped because of side effects.[1] Self-pay: $449 per 4-dose fill with on-time refills (otherwise $699).[5]
How many units is 12.5 mg of tirzepatide?
12.5 mg = 50 units from a 12.5 mg single-dose vial (the whole 0.5 mL, 25 mg/mL) and 60 units from a 12.5 mg multi-dose vial (0.6 mL at 20.83 mg/mL). From a 10 mg/mL solution it is 125 units; from 20 mg/mL, 62.5 units.
12.5 mg is the last step before the maximum, reached at week 17 at the earliest. Like 7.5 mg, it is not a listed Zepbound maintenance dose.[1] It was one of the last two strengths to become available as a single-dose vial: prescribing began in July 2025 and vials shipped from early August 2025.[8] In a multi-dose vial the four 12.5 mg doses add up to 50 mg in 2.4 mL (20.83 mg/mL), the second-strongest of the multi-dose vials.[1] Self-pay: $449 per 4-dose fill with on-time refills (otherwise $699).[5]
How many units is 15 mg of tirzepatide?
15 mg = 50 units from a 15 mg single-dose vial (the whole 0.5 mL, 30 mg/mL) and 60 units from a 15 mg multi-dose vial (0.6 mL at 25 mg/mL). From a 10 mg/mL solution it is 150 units; from 20 mg/mL, 75 units.
15 mg once weekly is the highest dose in both labels and is reached at week 21 at the earliest.[1][2] SURMOUNT-1 reported −20.9% average weight change, with 56.7% losing 20% or more; in people with type 2 diabetes (SURMOUNT-2) the figure was −14.7%.[3][1] Vomiting (13%) and diarrhea (23%) were most common at this dose.[1] Because the self-pay price is the same from 7.5 mg up, 15 mg works out cheapest per milligram: $449 per 4-dose fill with on-time refills (otherwise $699).[5] The 15 mg single-dose vial is the most concentrated solution in the label at 30 mg/mL; the 15 mg multi-dose vial is 25 mg/mL.[1]
More tirzepatide math
- Tirzepatide calculatorAny vial, any dose
- Units to mg chartBoth directions, every concentration
- Dose escalation chartWhen each dose starts
- Cost per dosePrices worked out per mg
Frequently asked questions
How many units is 2.5 mg of tirzepatide?
50 units from a 2.5 mg single-dose vial (the whole 0.5 mL), 60 units from a 10 mg multi-dose vial (0.6 mL), or 25 units from a 10 mg/mL solution.
How many units is 5 mg of tirzepatide?
50 units from a 5 mg single-dose vial, 60 units from a 5 mg multi-dose vial, 50 units at 10 mg/mL and 25 units at 20 mg/mL.
How many units is 7.5 mg of tirzepatide?
50 units from a 7.5 mg single-dose vial, 60 from a 7.5 mg multi-dose vial, 75 at 10 mg/mL and 37.5 at 20 mg/mL.
How many units is 10 mg of tirzepatide?
50 units from a 10 mg single-dose vial, 60 from a 10 mg multi-dose vial, a full 100 at 10 mg/mL, and 50 at 20 mg/mL.
Why is every single-dose vial 50 units?
Each strength is dissolved in the same 0.5 mL. Only the concentration changes, from 5 mg/mL (2.5 mg) to 30 mg/mL (15 mg).[1]
Sources
- Zepbound (tirzepatide) injection: prescribing information, Medication Guide and Instructions for Use
- Mounjaro (tirzepatide) injection: prescribing information and Instructions for Use
- Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1)
- Frías JP et al. Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2)
- Zepbound on LillyDirect: formats and self-pay prices
- Lilly releases Zepbound single-dose vials, expanding supply and access
- Lilly launches additional Zepbound vial doses and offers new savings for self-pay patients
- Lilly to offer all approved doses of Zepbound single-dose vials through LillyDirect
- FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products
- FDA's concerns with unapproved GLP-1 drugs used for weight loss