Semaglutide reconstitution table
What different amounts of water give you, for each quick-pick vial size. This is arithmetic, not a recommendation: the right amount of water is whatever makes your measurements easy and matches any instructions you were given.
| Vial | Water | Concentration | Per unit (0.01 mL) | Per 10 units (0.1 mL) |
|---|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 50 mcg | 500 mcg |
| 5 mg | 2 mL | 2.5 mg/mL | 25 mcg | 250 mcg |
| 5 mg | 3 mL | 1.67 mg/mL | 16.67 mcg | 167 mcg |
| 10 mg | 1 mL | 10 mg/mL | 100 mcg | 1 mg |
| 10 mg | 2 mL | 5 mg/mL | 50 mcg | 500 mcg |
| 10 mg | 3 mL | 3.33 mg/mL | 33.33 mcg | 333 mcg |
How the math works for Semaglutide
A 10 mg Semaglutide vial holds 10,000 mcg. Mixed with 2 mL of water, that's 10,000 ÷ 2 = 5,000 mcg per mL. One unit on a U-100 syringe is 0.01 mL, so each unit holds 50 mcg. More water spreads the same 10 mg across more units; less water packs it into fewer.
mcg per unit = concentration ÷ 100
Units to draw = amount (mcg) ÷ mcg per unit
Brand-name semaglutide doesn't need mixing
FDA-approved semaglutide injections come as a ready-to-use liquid. Ozempic's prescribing information, for example, lists prefilled pens holding 2 mg, 4 mg or 8 mg of semaglutide in 3 mL of solution. If you have a powder vial that needs water added, it isn't one of the FDA-approved products. It's a compounded or unapproved version.
The FDA says unapproved GLP-1 drugs don't go through its review for safety, effectiveness and quality, and it has received reports of dosing errors with compounded injectable semaglutide, some of which needed hospital care, including cases where the dose was miscalculated. If a pharmacy compounded yours, follow its label and your prescriber exactly, and use this calculator only to double-check the arithmetic.
What is Semaglutide?
Semaglutide is the active ingredient in Ozempic, Wegovy and Rybelsus, FDA-approved prescription drugs from Novo Nordisk. It belongs to the class of drugs called GLP-1 receptor agonists.
Frequently asked questions
How much water do I add to a 10 mg Semaglutide vial?
There's no single right amount. Less water makes each unit stronger and harder to measure; more water makes each unit weaker and easier to measure. For a 10 mg vial, 1 mL gives 100 mcg per unit, 2 mL gives 50 mcg, and 3 mL gives 33.33 mcg. If your Semaglutide was prescribed, use the amount in your prescription instructions.
How many mcg of Semaglutide are in one unit?
It depends on the vial size and how much water you add: mcg per unit = (mg in the vial × 1,000) ÷ (mL of water × 100). With a 10 mg vial and 2 mL of water, that's 50 mcg per unit on a U-100 syringe.
Is Semaglutide FDA approved?
Yes. Approved for type 2 diabetes and, as Wegovy, for weight management. In February 2026 the FDA announced restrictions on the ingredients used in mass-marketed compounded versions.
Other peptide calculators
General reconstitution calculator · Peptide FDA status tracker