Milligrams to millilitres needs the concentration, not a density. Tables at 2.5 to 20 mg/mL, mL back to mg, and the volumes the GLP-1 pens deliver.
"Mg to mL" is one of the most searched conversions there is, and most converters answer it by assuming the liquid is water. For a peptide or GLP-1 solution that assumption is the wrong one. A dose is a few milligrams of drug dissolved in a volume of liquid, and the only figure that turns those milligrams into millilitres is how much drug each millilitre holds — the concentration, in mg/mL. This page sets out that one step, in both directions, with tables and the volumes the approved pens actually deliver. It reports arithmetic and label figures; it sets no dose.
Two neighbouring conversions sit on their own pages: milligrams to syringe units, which is this page's answer multiplied by 100, and milligrams to micrograms, which is a change of scale rather than a change from mass to volume. For tirzepatide, the same conversion is tabulated in both directions, milligrams to units and units to milligrams, at five concentrations on tirzepatide dosage in units.
| Direction |
Formula |
Example at 5 mg/mL |
| Milligrams to millilitres |
mL = mg ÷ mg/mL |
2.5 mg ÷ 5 = 0.5 mL |
| Millilitres to milligrams |
mg = mL × mg/mL |
0.5 mL × 5 = 2.5 mg |
| Millilitres to U-100 units |
units = mL × 100 |
0.5 mL = 50 units |
The concentration has to come from somewhere. On an approved product it is printed on the label. On a vial of powder it is created at reconstitution: the vial's milligrams divided by the millilitres of water added. A 10 mg vial with 2 mL is 5 mg/mL; the same vial with 1 mL is 10 mg/mL. The volumes for each compound and vial size are on the reconstitution pages, and the reconstitution calculator does the division for any combination.
How many mL is a given number of milligrams
| Amount |
2.5 mg/mL |
5 mg/mL |
10 mg/mL |
20 mg/mL |
| 0.25 mg |
0.1 mL |
0.05 mL |
0.025 mL |
0.0125 mL |
| 0.5 mg |
0.2 mL |
0.1 mL |
0.05 mL |
0.025 mL |
| 1 mg |
0.4 mL |
0.2 mL |
0.1 mL |
0.05 mL |
| 2 mg |
0.8 mL |
0.4 mL |
0.2 mL |
0.1 mL |
| 2.5 mg |
1 mL |
0.5 mL |
0.25 mL |
0.125 mL |
| 5 mg |
2 mL |
1 mL |
0.5 mL |
0.25 mL |
| 7.5 mg |
3 mL |
1.5 mL |
0.75 mL |
0.375 mL |
| 10 mg |
4 mL |
2 mL |
1 mL |
0.5 mL |
| 15 mg |
6 mL |
3 mL |
1.5 mL |
0.75 mL |
The table shows why the same milligram figure can be a comfortable volume or an impossible one. At 2.5 mg/mL anything above 2.5 mg is more than 1 mL — more than a 1 mL syringe holds and more than the 1 mL the Open RN nursing text cited on the injection guide gives as the upper limit for a subcutaneous injection in adults. At 20 mg/mL the small amounts fall to hundredths of a millilitre, below the finest marks most barrels carry.
How many milligrams are in a given volume
| Volume |
Units (U-100) |
2.5 mg/mL |
5 mg/mL |
10 mg/mL |
20 mg/mL |
| 0.05 mL |
5 |
0.125 mg |
0.25 mg |
0.5 mg |
1 mg |
| 0.1 mL |
10 |
0.25 mg |
0.5 mg |
1 mg |
2 mg |
| 0.25 mL |
25 |
0.625 mg |
1.25 mg |
2.5 mg |
5 mg |
| 0.5 mL |
50 |
1.25 mg |
2.5 mg |
5 mg |
10 mg |
| 1 mL |
100 |
2.5 mg |
5 mg |
10 mg |
20 mg |
Read across a row and the point of the whole conversion is visible: half a millilitre is 1.25 mg or 10 mg depending on nothing but the concentration — an eightfold spread from the same mark on the same syringe.
The volumes the approved GLP-1 products deliver
The approved products fix one of the two numbers so that nobody has to compute the other. Read from the labels on 2026-10-02:
| Product (label) |
Dose |
Volume per dose |
Concentration |
| Ozempic multi-dose pen |
0.25 mg |
about 0.37 mL |
0.68 mg/mL |
| Ozempic multi-dose pen |
0.5 mg |
about 0.74 mL |
0.68 mg/mL |
| Ozempic multi-dose pen |
1 mg |
about 0.75 mL |
1.34 mg/mL |
| Ozempic multi-dose pen |
2 mg |
about 0.75 mL |
2.68 mg/mL |
| Wegovy single-dose pen |
0.25, 0.5, 1 mg |
0.5 mL |
0.5, 1, 2 mg/mL |
| Wegovy single-dose pen |
1.7, 2.4 mg |
0.75 mL |
2.27, 3.2 mg/mL |
| Wegovy HD single-dose pen |
7.2 mg |
0.75 mL |
9.6 mg/mL |
| Zepbound / Mounjaro single-dose |
2.5–15 mg |
0.5 mL |
5–30 mg/mL |
| Zepbound / Mounjaro KwikPen and multi-dose vial |
2.5–15 mg |
0.6 mL |
4.17–25 mg/mL |
The Ozempic volumes are this site's division of each dose by the label's printed concentration. One detail of that label is worth stating rather than smoothing over: its pens are listed as 2 mg, 4 mg and 8 mg in 3 mL, which divides to 0.67, 1.33 and 2.67 mg/mL, while the printed concentrations are 0.68, 1.34 and 2.68 mg/mL. The sections read do not explain the small difference; the volumes above use the printed figures. How the Ozempic pen's dial converts a dose into clicks is on Ozempic pen clicks, and the tirzepatide presentations are set out on where to inject tirzepatide.
Where the conversion goes wrong
The FDA's MedWatch bulletin of 2024-07-29 on compounded semaglutide is the regulator's own record of this conversion failing. It reported patients who drew five to 20 times the intended dose from multi-dose vials, some of whom needed hospital care, and named "confusion between different units of measurement (e.g., milliliters, milligrams and 'units')" as a possible contributor, alongside unfamiliarity with drawing from a vial. The semaglutide amounts behind that bulletin are converted to syringe units at four compounded concentrations, in both directions, on semaglutide dosage in units.
Three mix-ups account for most tenfold errors, and each is a confusion of what a number measures:
- mg read as mL. "Draw 0.5" means 0.5 mL at one concentration and a very different volume if the 0.5 was milligrams. At 2.5 mg/mL, 0.5 mg is 0.2 mL, not 0.5 mL.
- mL read as units. 0.1 mL is 10 units on a U-100 syringe, not 1. A misplaced decimal between the two is a tenfold change.
- A concentration carried over from another vial. A unit or millilitre figure copied from a 5 mg/mL vial means twice the drug in a 10 mg/mL vial.
- Micrograms divided by mg/mL. An amount in mcg needs the concentration in mcg/mL; the tables for that case are on mcg to mL.
Reading the marks themselves is covered on reading an insulin syringe.
What the arithmetic cannot settle
The formula is exact; the inputs are not always. A lyophilised vial's stated milligrams are what the maker claims, and a research vial carries no regulator-reviewed label, so its true concentration after reconstitution is only as good as that claim and the water measured into it. The volume that leaves a syringe also differs slightly from the mark because of the space in the hub and needle. None of this changes the conversion; it limits how much a calculated volume can promise. Storage and the general mixing procedure are covered on Medibact's how to store peptides and how to reconstitute peptides pages. Nothing on this page is an instruction; dose and technique belong with the prescriber.
Sources and dates
Opened 2026-10-02: the OZEMPIC injection label via openFDA (Novo Nordisk, effective 2026-07-30), sections 2 and 3; the WEGOVY injection and tablet label via DailyMed (set id ee06186f-2aa3-4990-a760-757579d8f77b, effective 2026-06-18), sections 2 and 3; the ZEPBOUND label via openFDA (effective 2026-08-28) and the MOUNJARO label via openFDA (effective 2026-07-29), section 3; the FDA MedWatch bulletin of 2024-07-29 on dosing errors with compounded semaglutide. Conversions and volumes are arithmetic by this site. Corrections go to the contact page.
