How much bacteriostatic water do I mix with 5mg semaglutide?

No FDA label answers this, because no FDA-approved semaglutide comes as a powder. The volume on a compounded vial is set by the dispensing pharmacy's instructions and the prescriber. The arithmetic for any choice is simple: 5 mg in 1 mL is 5 mg/mL, in 2 mL is 2.5 mg/mL, and in 3 mL is about 1.667 mg/mL. Compounded semaglutide is not FDA approved.

What is a semaglutide reconstitution chart?

It is a lookup table that pairs a vial size (for example 2, 5, 10 or 20 mg) with a water volume (1, 2 or 3 mL) and shows the resulting concentration and the U-100 syringe units for a given dose. The math is concentration = vial mg ÷ water mL, then units = dose mg ÷ concentration × 100. It applies only to lyophilized vials, not to Wegovy or Ozempic pens.

Do you reconstitute Ozempic or Wegovy?

No. Ozempic and Wegovy are supplied as ready-to-use solutions in pens or single-dose syringes, and Wegovy also comes as tablets. The labels give no mixing step. Ozempic pens are labeled 2 mg/3 mL (0.68 mg/mL), 4 mg/3 mL (1.34 mg/mL) and 8 mg/3 mL (2.68 mg/mL); the Wegovy FlexTouch pen is 9.6 mg/3 mL (3.2 mg/mL).

How many units is 0.25 mg of semaglutide in a 5mg vial?

It depends on the water volume. With 1 mL (5 mg/mL), 0.25 mg is 5 units; with 2 mL (2.5 mg/mL), it is 10 units; with 3 mL (about 1.667 mg/mL), it is 15 units. Each figure is 0.25 ÷ concentration × 100 on a U-100 syringe. Follow the pharmacy label and the prescription.

Is compounded semaglutide legal?

The FDA declared the semaglutide injection shortage resolved on February 21, 2025. Its enforcement discretion for copies ended April 22, 2025 for 503A pharmacies and May 22, 2025 for 503B outsourcing facilities. FDA says compounded drugs are not FDA approved, and on February 6, 2026 it announced intent to restrict GLP-1 ingredients used in non-approved compounded drugs. Ask your prescriber about FDA-approved options.

What is the semaglutide reconstitution chart for a 10mg vial?

With 1 mL of water a 10 mg vial is 10 mg/mL, with 2 mL it is 5 mg/mL, and with 3 mL it is about 3.333 mg/mL. At 5 mg/mL the five Wegovy label steps work out to 5, 10, 20, 34 and 48 units on a U-100 syringe (0.25, 0.5, 1, 1.7 and 2.4 mg). This is arithmetic for a compounded vial, which is not FDA approved; follow the pharmacy label and prescription.

Semaglutide Reconstitution Chart (Vial × Water → Units)

5 sources
No vendors

Short answer

Wegovy and Ozempic are ready-to-use pens and are never reconstituted. For a lyophilized compounded vial, concentration = vial mg ÷ water mL and U-100 units = dose mg ÷ concentration × 100. Example: 5 mg with 2 mL gives 2.5 mg/mL, so 0.25 mg = 10 units. Compounded semaglutide is not FDA approved. Checked Oct 19, 2026.

On this page8 sections

Semaglutide reconstitution chart: concentration by vial and water
Units for each label dose step
How many label-size doses a vial represents
Why Wegovy and Ozempic are never reconstituted
Compounded semaglutide: regulatory status
Reading the math safely
FAQ
Sources

Key facts (as of Oct 19, 2026)
Item	Value	Source
FDA-approved semaglutide forms	Prefilled pens, single-dose syringes and tablets; none is a powder	Novo Nordisk, Jun 18, 2026
Ozempic pen concentrations (labeled)	0.68, 1.34 and 2.68 mg/mL	Novo Nordisk, Jun 1, 2026
Wegovy FlexTouch concentration	9.6 mg/3 mL (3.2 mg/mL)	Novo Nordisk, Jun 18, 2026
Semaglutide shortage resolved	February 21, 2025	FDA, Feb 21, 2025
503A enforcement discretion ended	April 22, 2025	FDA, Feb 21, 2025
503B enforcement discretion ended	May 22, 2025	FDA, Feb 21, 2025
FDA statement on non-approved GLP-1s	February 6, 2026	FDA, Feb 6, 2026
Compounded drug status	Not approved by FDA	FDA, Apr 1, 2026

Also useful: Semaglutide mg to units, Reconstitution (any vial).

From vial to syringe: a semaglutide worked example in three steps

Vial and water
5 mg + 2 mL
The mg in the vial never changes; water only sets how spread out it is.
Concentration
5 ÷ 2 = 2.5 mg/mL
Milligrams in every milliliter of solution.
Units on a U-100 syringe
0.5 mg ÷ 2.5 = 0.2 mL = 20 U
100 units = 1 mL, so units = mL × 100 (rounded to 0.5 U).

Reconstitution means adding a measured volume of sterile liquid to a freeze-dried (lyophilized) powder so it becomes a solution. Branded semaglutide never needs this step. The arithmetic below applies only to lyophilized compounded or research vials, which are not FDA approved and are not interchangeable with Wegovy or Ozempic.

Semaglutide reconstitution chart: concentration by vial and water

Concentration is the vial’s mg divided by the mL of water added. The table covers the four vial sizes most often printed on compounded labels and three common water volumes.

Semaglutide concentration (mg/mL) by vial size and water volume (arithmetic: vial mg ÷ water mL)
Vial	1 mL water	2 mL water	3 mL water
2 mg	2 mg/mL	1 mg/mL	0.667 mg/mL
5 mg	5 mg/mL	2.5 mg/mL	1.667 mg/mL
10 mg	10 mg/mL	5 mg/mL	3.333 mg/mL
20 mg	20 mg/mL	10 mg/mL	6.667 mg/mL

More water means a weaker solution and more units for the same mg. Less water means a stronger solution and fewer units, where small reading errors on the syringe matter more.

Units for each label dose step

The matrix below converts the five Wegovy label steps (0.25, 0.5, 1, 1.7 and 2.4 mg) into units on a U-100 insulin syringe. U-100 means 100 units per mL, so 1 unit is 0.01 mL. The doses are used only because they are the published label steps; they are not a recommendation for any compounded product. (Novo Nordisk, Jun 18, 2026)

U-100 syringe units for each Wegovy label step, by vial size and water volume. Arithmetic only: units = dose mg ÷ (vial mg ÷ water mL) × 100. A dash means more than 100 units (over 1 mL) or more than the vial holds.

2 mg vial: U-100 units to draw for each dose (1 mL = 2 mg/mL; 2 mL = 1 mg/mL; 3 mL = 0.667 mg/mL)
Dose	1 mL water2 mg/mL	2 mL water1 mg/mL	3 mL water0.667 mg/mL
0.25 mg	12.5 U	25 U	37.5 U
0.5 mg	25 U	50 U	75 U
1 mg	50 U	100 U	—
1.7 mg	85 U	—	—
2.4 mg	—	—	—

5 mg vial: U-100 units to draw for each dose (1 mL = 5 mg/mL; 2 mL = 2.5 mg/mL; 3 mL = 1.667 mg/mL)
Dose	1 mL water5 mg/mL	2 mL water2.5 mg/mL	3 mL water1.667 mg/mL
0.25 mg	5 U	10 U	15 U
0.5 mg	10 U	20 U	30 U
1 mg	20 U	40 U	60 U
1.7 mg	34 U	68 U	—
2.4 mg	48 U	96 U	—

10 mg vial: U-100 units to draw for each dose (1 mL = 10 mg/mL; 2 mL = 5 mg/mL; 3 mL = 3.333 mg/mL)
Dose	1 mL water10 mg/mL	2 mL water5 mg/mL	3 mL water3.333 mg/mL
0.25 mg	2.5 U	5 U	7.5 U
0.5 mg	5 U	10 U	15 U
1 mg	10 U	20 U	30 U
1.7 mg	17 U	34 U	51 U
2.4 mg	24 U	48 U	72 U

20 mg vial: U-100 units to draw for each dose (1 mL = 20 mg/mL; 2 mL = 10 mg/mL; 3 mL = 6.667 mg/mL)
Dose	1 mL water20 mg/mL	2 mL water10 mg/mL	3 mL water6.667 mg/mL
0.25 mg	1.5 U (raw 1.25)	2.5 U	4 U (raw 3.75)
0.5 mg	2.5 U	5 U	7.5 U
1 mg	5 U	10 U	15 U
1.7 mg	8.5 U	17 U	25.5 U
2.4 mg	12 U	24 U	36 U

Units = dose mg ÷ (vial mg ÷ water mL) × 100, rounded to the nearest 0.5 U; the raw value is shown in brackets when rounding changed it. A dash means the draw would exceed a 100-unit syringe or the vial. Arithmetic only; not dosing advice.

Worked examples

Worked reconstitution examples (arithmetic)
Vial and water	Concentration	Dose	Units	Volume
5 mg + 2 mL	2.5 mg/mL	0.25 mg	10 U	0.10 mL
5 mg + 2 mL	2.5 mg/mL	1 mg	40 U	0.40 mL
10 mg + 2 mL	5 mg/mL	1.7 mg	34 U	0.34 mL
10 mg + 3 mL	3.333 mg/mL	2.4 mg	72 U	0.72 mL
2 mg + 1 mL	2 mg/mL	0.5 mg	25 U	0.25 mL
20 mg + 1 mL	20 mg/mL	0.25 mg	2.5 U	0.025 mL

The last row shows why very concentrated solutions are hard to measure. At 20 mg/mL, a 0.25 mg dose is 2.5 units, which sits between the marks on most syringes. A 2 mg vial at 2.4 mg is blank in the matrix for a different reason: the vial holds less than one dose of that size.

Run your own numbers in the semaglutide reconstitution calculator or the semaglutide units calculator, which use the same formula.

How many label-size doses a vial represents

Dividing the vial’s total mg by a dose gives the number of doses of that size the vial contains, before any loss in the syringe or vial. It is a quick check that a vial label and a prescription agree.

Doses of each label size contained in a vial (arithmetic: vial mg ÷ dose mg, rounded down)
Vial	0.25 mg	0.5 mg	1 mg	1.7 mg	2.4 mg
2 mg	8	4	2	1	0
5 mg	20	10	5	2	2
10 mg	40	20	10	5	4
20 mg	80	40	20	11	8

For comparison, a branded Ozempic 2 mg/3 mL pen holds 2 mg in total, and a Wegovy FlexTouch pen holds 9.6 mg for four 2.4 mg doses. (Novo Nordisk, Jun 1, 2026) (Novo Nordisk, Jun 18, 2026) Water volume does not change these counts; it only changes how many units each dose takes.

Why Wegovy and Ozempic are never reconstituted

Every FDA-approved semaglutide product arrives ready to use. The Wegovy label lists single-dose pens, single-dose syringes, the multi-dose FlexTouch pen and tablets. The Ozempic label lists multi-dose pens and single-dose prefilled syringes. None has a mixing step. (Novo Nordisk, Jun 18, 2026) (Novo Nordisk, Jun 1, 2026)

For context, the labels print the concentration of the multi-dose pens. These figures help when comparing a pharmacy label against a branded product. They are not instructions to draw medicine from a pen. Pens are designed to deliver the labeled doses through the pen itself.

Labeled concentration of multi-dose semaglutide pens (prescribing information, section 3)
Pen	Total and volume	Labeled concentration	Labeled doses
Ozempic	2 mg/3 mL	0.68 mg/mL	4 × 0.25 mg and 2 × 0.5 mg, or 4 × 0.5 mg
Ozempic	4 mg/3 mL	1.34 mg/mL	4 × 1 mg
Ozempic	8 mg/3 mL	2.68 mg/mL	4 × 2 mg
Wegovy FlexTouch	9.6 mg/3 mL	3.2 mg/mL	4 × 2.4 mg

(Novo Nordisk, Jun 1, 2026) (Novo Nordisk, Jun 18, 2026)

We report the concentrations exactly as the labels print them rather than recomputing them. Ozempic pens are dialed in mg, not in syringe units, and the label says a pen “must never be shared between patients, even if the needle is changed.” Wegovy single-dose pens hold 0.5 mL (0.25, 0.5 and 1 mg) or 0.75 mL (1.7, 2.4 and 7.2 mg).

Compounded semaglutide: regulatory status

Compounded semaglutide grew during a national shortage. That shortage is over, and the legal basis for mass compounding has narrowed.

Semaglutide shortage and compounding timeline (FDA)
Date	Event
March 2022	Wegovy added to the FDA drug shortage list
August 2022	Ozempic added to the FDA drug shortage list
February 21, 2025	FDA declaratory order: semaglutide injection shortage resolved
April 22, 2025	Enforcement discretion ends for 503A pharmacies and physicians
May 22, 2025	Enforcement discretion ends for 503B outsourcing facilities
February 6, 2026	FDA announces intent to restrict GLP-1 ingredients for non-approved compounded drugs
April 1, 2026	FDA compounding policy page clarified (content current as of this date)

(FDA, Feb 21, 2025) (FDA, Feb 6, 2026) (FDA, Apr 1, 2026)

Three points from FDA’s current compounding page stand out. First, “Compounded drugs are not approved by FDA.” Second, FDA may treat a product that adds another ingredient, such as vitamin B12, to semaglutide as “essentially a copy” of the approved drug. Third, FDA does not intend to act on copies when a compounder fills four or fewer prescriptions of that product in a calendar month. (FDA, Apr 1, 2026)

Semaglutide sold with a “research use” label is not FDA approved either, and it is not interchangeable with Wegovy or Ozempic. This site does not list sellers of any kind.

Reading the math safely

A few checks catch most arithmetic errors:

Units and mg are different scales. A unit is a volume mark (0.01 mL on a U-100 syringe); mg is the amount of drug. The same 0.5 mg dose is 5 units at 10 mg/mL and 50 units at 1 mg/mL.
Use the concentration printed on the vial label if the pharmacy pre-mixed it. Recalculate only when the label states the powder amount and the water volume.
If the result is over 100 units, it is more than 1 mL and more than one standard U-100 syringe.
Cross-check with a second method, such as the units calculator, before relying on a number.

For how these mg doses map to the label ladder, see the semaglutide dosage chart. For approvals and trial data, see the semaglutide hub. Questions about whether a product is right for you belong with your prescriber.

Frequently asked questions

How much bacteriostatic water do I mix with 5mg semaglutide?: No FDA label answers this, because no FDA-approved semaglutide comes as a powder. The volume on a compounded vial is set by the dispensing pharmacy's instructions and the prescriber. The arithmetic for any choice is simple: 5 mg in 1 mL is 5 mg/mL, in 2 mL is 2.5 mg/mL, and in 3 mL is about 1.667 mg/mL. Compounded semaglutide is not FDA approved.
What is a semaglutide reconstitution chart?: It is a lookup table that pairs a vial size (for example 2, 5, 10 or 20 mg) with a water volume (1, 2 or 3 mL) and shows the resulting concentration and the U-100 syringe units for a given dose. The math is concentration = vial mg ÷ water mL, then units = dose mg ÷ concentration × 100. It applies only to lyophilized vials, not to Wegovy or Ozempic pens.
Do you reconstitute Ozempic or Wegovy?: No. Ozempic and Wegovy are supplied as ready-to-use solutions in pens or single-dose syringes, and Wegovy also comes as tablets. The labels give no mixing step. Ozempic pens are labeled 2 mg/3 mL (0.68 mg/mL), 4 mg/3 mL (1.34 mg/mL) and 8 mg/3 mL (2.68 mg/mL); the Wegovy FlexTouch pen is 9.6 mg/3 mL (3.2 mg/mL).
How many units is 0.25 mg of semaglutide in a 5mg vial?: It depends on the water volume. With 1 mL (5 mg/mL), 0.25 mg is 5 units; with 2 mL (2.5 mg/mL), it is 10 units; with 3 mL (about 1.667 mg/mL), it is 15 units. Each figure is 0.25 ÷ concentration × 100 on a U-100 syringe. Follow the pharmacy label and the prescription.
Is compounded semaglutide legal?: The FDA declared the semaglutide injection shortage resolved on February 21, 2025. Its enforcement discretion for copies ended April 22, 2025 for 503A pharmacies and May 22, 2025 for 503B outsourcing facilities. FDA says compounded drugs are not FDA approved, and on February 6, 2026 it announced intent to restrict GLP-1 ingredients used in non-approved compounded drugs. Ask your prescriber about FDA-approved options.
What is the semaglutide reconstitution chart for a 10mg vial?: With 1 mL of water a 10 mg vial is 10 mg/mL, with 2 mL it is 5 mg/mL, and with 3 mL it is about 3.333 mg/mL. At 5 mg/mL the five Wegovy label steps work out to 5, 10, 20, 34 and 48 units on a U-100 syringe (0.25, 0.5, 1, 1.7 and 2.4 mg). This is arithmetic for a compounded vial, which is not FDA approved; follow the pharmacy label and prescription.

Sources

Declaratory Order: Resolution of Shortages of Semaglutide Injection Products (Ozempic and Wegovy). U.S. Food and Drug Administration, Feb 21, 2025. Accessed Oct 19, 2026.
FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize. U.S. Food and Drug Administration, Apr 1, 2026. Accessed Oct 19, 2026.
FDA Intends to Take Action Against Non-FDA-Approved GLP-1 Drugs. U.S. Food and Drug Administration, Feb 6, 2026. Accessed Oct 19, 2026.
OZEMPIC (semaglutide) injection, for subcutaneous use - Full Prescribing Information (SPL). Novo Nordisk / National Library of Medicine DailyMed, Jun 1, 2026. Accessed Oct 19, 2026.
WEGOVY (semaglutide) injection, for subcutaneous use; WEGOVY (semaglutide) tablets, for oral use - Full Prescribing Information (SPL, Revised 6/2026). Novo Nordisk / National Library of Medicine DailyMed, Jun 18, 2026. Accessed Oct 19, 2026.