What is semaglutide?
Before any semaglutide dosing chart makes sense, it helps to know what is in the vial. Semaglutide is a GLP-1 receptor agonist developed by Novo Nordisk. It is a modified version of the natural hormone GLP-1, with a fatty acid side chain attached so it binds to albumin in the blood and lasts far longer than the native hormone. Novo Nordisk has also studied it alongside cagrilintide in a combination called CagriSema.
The approved products come ready to use: injection pens and oral tablets, labeled in mg. Research-labeled and compounded semaglutide is different. It is usually a vial of freeze-dried powder, commonly 2 mg, 5 mg or 10 mg, that has to be mixed with bacteriostatic water before any syringe unit means anything. That mixing step is what this page is about.
How much BAC water for a semaglutide vial?
There is no universal volume. The water you add only sets the concentration, and the concentration decides how many units a given amount takes. The semaglutide reconstitution chart below shows mcg per unit for the three common vial sizes across several water volumes.
| BAC water | 2 mg vial | 5 mg vial | 10 mg vial |
|---|---|---|---|
| 1 mL | 20 mcg/unit 2 mg/mL | 50 mcg/unit 5 mg/mL | 100 mcg/unit 10 mg/mL |
| 2 mL | 10 mcg/unit 1 mg/mL | 25 mcg/unit 2.5 mg/mL | 50 mcg/unit 5 mg/mL |
| 3 mL | 6.67 mcg/unit 0.667 mg/mL | 16.67 mcg/unit 1.667 mg/mL | 33.33 mcg/unit 3.333 mg/mL |
| 4 mL | 5 mcg/unit 0.5 mg/mL | 12.5 mcg/unit 1.25 mg/mL | 25 mcg/unit 2.5 mg/mL |
Each cell shows mcg per unit on a U-100 syringe (100 units = 1 mL) and the resulting concentration.
Read down a column to follow one vial size, such as a semaglutide 5mg vial, as more water is added: each cell gets smaller, so the same amount needs more units. Read across a row to compare vial sizes at the same volume. The cells come from one formula: vial mg × 1,000 ÷ (water mL × 100). For the general mixing process, see how peptides are reconstituted.
Worked example with the semaglutide calculator
Here is the arithmetic the semaglutide calculator runs. For example, if the amount you already have is 0.3 mg and a 5 mg vial is mixed with 2 mL of BAC water:
The math: 5 mg ÷ 2 mL = 2.5 mg/mL (2,500 mcg/mL), which is 25 mcg per unit. 0.3 mg ÷ 2,500 mcg/mL = 0.12 mL = 12 units on a U-100 syringe.
Now the semaglutide 10mg vial case. For example, if the amount you already have is 0.6 mg and a 10 mg vial is mixed with 2 mL:
The math: 10 mg ÷ 2 mL = 5 mg/mL (5,000 mcg/mL), which is 50 mcg per unit. 0.6 mg ÷ 5,000 mcg/mL = 0.12 mL = 12 units on a U-100 syringe.
The method is always three steps: vial mg ÷ water mL gives mg/mL; the amount ÷ mg/mL gives mL; mL × 100 gives units. Units only work this way on a U-100 syringe, where 1 unit is 0.01 mL. The U-100 units to mL chart shows the scale at a glance.
Semaglutide dosing chart: what the numbers mean
A semaglutide dosing chart on this site is a conversion table, not a protocol. It tells you how many mcg sit in each syringe unit for a given vial and water volume. It does not tell you what amount to use or how often. Those come from the product labeling for the approved drugs and from a qualified professional; a semaglutide dosing calculator cannot supply them.
Two situations cause most confusion. First, approved pens are already in solution and labeled by the mg they deliver, so pen “clicks” and syringe units are unrelated. Second, a semaglutide 10mg vial dosage chart and a 5 mg chart give different unit counts for the same amount, even at the same water volume. If a number looks wrong, the guide to checking calculator math shows how to redo it by hand.
Semaglutide units to mg and units to mL
People also search the other direction: “semaglutide units to mg”. The formula runs backwards cleanly. Take the units on a U-100 syringe and divide by 100 to get mL. Multiply the mL by the concentration in mg/mL to get mg. Put together: mg = units × (vial mg ÷ water mL) ÷ 100.
So “semaglutide units to ml” never depends on the vial: 100 units is always 1 mL. “Units to mg” always depends on the vial and water, which is why a units figure without the concentration is meaningless. Remember 1 mg = 1,000 mcg when switching between the two; the mg to mcg conversion guide has a quick table.
Semaglutide reconstitution notes from labeling
Some suppliers specify bacteriostatic water as the diluent, adding it slowly down the side of the vial and swirling rather than shaking, and refrigerating once mixed. Some compounded products arrive already in solution with a stated mg/mL; in that case there is no mixing step, and mcg per unit is simply mg/mL × 10. Some compounded labels also list added ingredients; the calculator tracks only the semaglutide mg the label states. These notes describe labeling, not instructions from this site. For the diluent itself, read what bacteriostatic water is.
Is semaglutide FDA-approved?
Yes, as specific branded products. Semaglutide is FDA-approved as Ozempic (injection, 2017), Rybelsus (tablets, 2019) and Wegovy (injection, 2021), all made by Novo Nordisk. Research-labeled and compounded vials are not those products, and a correct calculation says nothing about their identity, purity, sterility or content. For a related dual-agonist calculator, see tirzepatide.
Semaglutide FAQ
How much BAC water do you add to a 5 mg semaglutide vial?
There is no single required volume. The water only sets the concentration. The chart on this page shows mcg per unit for several volumes; the product labeling decides the diluent and volume.
How do I convert semaglutide units to mg?
Divide the units by 100 to get mL, then multiply by the concentration in mg/mL. The concentration is the vial mg divided by the mL of water added, so the answer changes with every vial and water volume.
How many mL is a unit on the syringe?
On a U-100 syringe, 1 unit is 0.01 mL and 100 units is 1 mL. This does not depend on the semaglutide vial; only the mg per unit does.
Is this a semaglutide dosing calculator?
It converts an amount you already have into mL and U-100 syringe units, or units back into mg. It does not recommend a dose, schedule or treatment.
Are semaglutide vials the same as Ozempic or Wegovy?
No. Ozempic, Wegovy and Rybelsus are FDA-approved Novo Nordisk products. Research-labeled or compounded vials are different products, and approved pens are not measured in syringe units.