How many doses a peptide vial holds: the one division, tables for tirzepatide, semaglutide, retatrutide and BPC-157 vials, and what the labelled devices state.
"How many doses in a 10 mg vial" has an exact answer, and it is one division: the milligrams in the vial divided by the milligrams in each dose. What confuses it is the water. Adding more bacteriostatic water feels like it should stretch a vial, but water adds volume, not peptide. This page gives the division, the tables for the vial sizes this site's calculator uses, and what the approved tirzepatide and semaglutide devices state about their own dose counts.
The same division applied to a labelled single-use vial and two research vial sizes is worked on thymosin alpha-1 reconstitution, where a 10 mg vial holds six of the label's 1.6 mg amounts. Turning a dose into a volume is a separate step, covered on mg to units and, for one compound, on tirzepatide dosage in units. The syringe scale itself is explained on insulin syringe units. At the other extreme, a compound dosed in whole milligrams, a 10 mg vial holds two of the 4 mg trial amounts, as shown on the ARA-290 reconstitution page.
The division, and what water does not change
Doses per vial = vial mg ÷ dose mg. The same 10 mg vial at three water volumes:
| Water added |
Concentration |
2.5 mg is |
Doses of 2.5 mg |
| 1 mL |
10 mg/mL |
25 units |
4 |
| 2 mL |
5 mg/mL |
50 units |
4 |
| 3 mL |
3.33 mg/mL |
75 units |
4 |
The volume decides how readable each dose is on a syringe; the milligrams decide how many there are. A dose counted in units carried from one water volume to another changes the milligrams, which is the error the peptide calculator exists to prevent.
What the labelled devices state
The approved GLP-1 devices print their own dose counts, which makes them the cleanest check on the arithmetic.
| Device |
Contents |
Doses stated |
Per dose |
| ZEPBOUND single-dose pen or vial |
One dose in 0.5 mL |
1 |
2.5–15 mg |
| ZEPBOUND multi-dose vial, 2.5 mg |
10 mg in 2.4 mL (4.17 mg/mL) |
4 |
0.6 mL |
| ZEPBOUND multi-dose vial, 15 mg |
60 mg in 2.4 mL (25 mg/mL) |
4 |
0.6 mL |
| ZEPBOUND KwikPen, 2.5 mg |
10 mg in 2.4 mL (4.17 mg/mL) |
4 |
0.6 mL |
| MOUNJARO KwikPen |
2.4 mL, extra volume for priming |
4, then the pen stops |
0.6 mL |
| WEGOVY FlexTouch |
9.6 mg in 3 mL (3.2 mg/mL) |
— |
9.6 mg is four 2.4 mg amounts |
The ZEPBOUND label's 2.5 mg multi-dose vial is the labelled answer to the 10 mg question: 10 mg, four weekly doses. The KwikPen statement matters for the next section. Lilly adds volume beyond the four doses so that priming does not eat into the last one, and the pen locks after the fourth.
Tirzepatide vials
| Dose |
10 mg vial |
15 mg vial |
30 mg vial |
| 2.5 mg |
4 |
6 |
12 |
| 5 mg |
2 |
3 |
6 |
| 7.5 mg |
1 (2.5 mg left) |
2 |
4 |
| 10 mg |
1 |
1 (5 mg left) |
3 |
| 12.5 mg |
0 |
1 (2.5 mg left) |
2 (5 mg left) |
| 15 mg |
0 |
1 |
2 |
At one dose a week, doses are weeks. The label's first step, four weeks at 2.5 mg, uses exactly 10 mg; the label's step-ups, set out on the Zepbound dose chart, are why a vial bought for one step often ends with a remainder at the next.
Semaglutide vials
| Dose |
5 mg vial |
10 mg vial |
| 0.25 mg |
20 |
40 |
| 0.5 mg |
10 |
20 |
| 1 mg |
5 |
10 |
| 1.7 mg |
2 (1.6 mg left) |
5 (1.5 mg left) |
| 2.4 mg |
2 (0.2 mg left) |
4 (0.4 mg left) |
Through the Wegovy label's ladder (four weeks each at 0.25, 0.5, 1 and 1.7 mg, then 2.4 mg), a 5 mg vial covers exactly the first ten weeks, ending on the second 1 mg dose, and a 10 mg vial covers thirteen weeks, ending on the first 1.7 mg dose with 1.3 mg left. The ladder itself is on the Wegovy dose chart.
Retatrutide and BPC-157 vials
| Compound and dose |
5 mg vial |
10 mg vial |
20 mg vial |
| Retatrutide 2 mg |
2 (1 mg left) |
5 |
10 |
| Retatrutide 4 mg |
1 (1 mg left) |
2 (2 mg left) |
5 |
| Retatrutide 12 mg |
0 |
0 |
1 (8 mg left) |
| BPC-157 250 mcg |
20 |
40 |
— |
| BPC-157 500 mcg |
10 |
20 |
— |
The retatrutide steps are those Lilly's releases describe for its trials; the compound is unapproved, and the figures are on the retatrutide dosage page. BPC-157's 250 and 500 mcg are vendor figures with no trial behind them, reported on the BPC-157 dosage page. For a twice-daily figure, divide the dose count by two to get days.
Why the count comes up short
The table assumes every microlitre leaves the vial. In practice some solution stays behind on each draw: in the vial's corners and stopper, in the needle and in the syringe hub. Lilly's KwikPen label deals with the same problem by adding volume "to allow for device priming". A research vial's label states its peptide content and nothing about overfill, so the shortfall lands on the last dose. No published figure for a typical loss per draw was found for this page, and how much remains depends on the syringe and the technique.
What this page does not cover
This page divides milligrams; it does not say what dose to use or how often. Every dose figure in the tables is a label step, a trial step or a vendor figure, named as such. Nothing here is a plan. The compounds are covered in Medibact's guides, for example the Tirzepatide guide and the Semaglutide guide, and dosing decisions belong with a prescriber.
Sources and dates
Opened 2026-10-10: the ZEPBOUND label via openFDA (version effective 2026-08-28), section 16.1. Carried from this site's pages with their read dates: the MOUNJARO KwikPen statements (DailyMed version published 2026-09-02, read 2026-10-04, on the Mounjaro pen page), the WEGOVY ladder and the FlexTouch contents (DailyMed, read 2026-09-18 and 2026-10-06), the retatrutide trial steps (retatrutide page, 2026-09-18) and the BPC-157 vendor figures (BPC-157 page, 2026-09-18). Research vial sizes are those the site's calculator lists. Every dose count and remainder is arithmetic by this site. Corrections go to the contact page.
