Semaglutide Reconstitution Chart: BAC Water, IU, and Vial Sizes (2026)

What This Semaglutide Reconstitution Chart Does (And What It Does Not)

This page does one job: it converts a semaglutide vial size plus a bacteriostatic water volume into exact insulin syringe units for every weekly dose from 0.25mg through 2.4mg. That is the whole point. You do not calculate anything here. You find your setup, run your eye across to your dose, and read the unit value.

A few things are handled elsewhere on purpose. For the step-by-step mixing procedure, including how to add water without foaming the powder and how to keep the process sterile, see the semaglutide reconstitution guide. For a deeper look at the 5mg vial on its own, the 5mg reference page goes further. And for why each dose sits where it does in the schedule, the dosing guide has the titration logic. Getting the units right matters: semaglutide has one of the largest clinical-trial bases of any GLP-1 medication, and the SELECT trial even showed a cardiovascular benefit, so the dose you draw should match the dose your protocol intends.

The Formula Behind Every Semaglutide Number

You do not need this to use the chart. It is here so you can trust the numbers. Every cell below comes from one formula:

Worked through once: take a 5mg vial and add 2mL of bacteriostatic water. The concentration is 5 ÷ 2 = 2.5mg/mL. For a 0.5mg dose, the units are (0.5 ÷ 2.5) × 100 = 20 IU on a U-100 syringe. Every value in the tables below is pre-calculated the same way, so you never have to.

The reconstitution math at a glance: vial size plus water sets the concentration, which sets the units.

Why Concentration Matters More Than Vial Size

This trips up almost everyone at first. The same 0.5mg dose is 20 units at 2.5mg/mL but only 10 units at 5mg/mL. The dose in milligrams has not changed; the concentration has. A more concentrated solution means a smaller volume, which means fewer units on the syringe for the same amount of drug. That is why the chart is organized by setup, not by dose alone. If your vial size or water volume is not one of the four below, the semaglutide calculator returns the exact units for any combination.

Semaglutide 5mg Vial Reconstitution Chart

The 5mg vial is the most common entry-point size for compounded semaglutide. Here are both standard reconstitutions for it, side by side with the full Wegovy titration.

5mg Vial + 2mL BAC Water (2.5mg/mL): The Recommended Setup

Using 2mL keeps every dose at or below 96 units, so the whole titration fits in a single U-100 syringe draw. This is why most compounding instructions default to it.

Vial longevity at 2.5mg/mL: 5mg / 0.25mg = 20 doses; 5mg / 0.5mg = 10 doses; 5mg / 1.0mg = 5 doses; 5mg / 2.4mg is approximately 2 doses.

5mg Vial + 2.5mL BAC Water (2mg/mL): Use With Caution at 2.4mg

Adding 2.5mL gives a slightly more dilute 2mg/mL solution. That makes very small starter-dose volumes a little easier to read, but it pushes the 2.4mg maintenance dose past a single syringe.

Why the 2mL reconstitution wins for the 2.4mg dose: 96 units fits one syringe, 120 units does not.

Semaglutide 10mg Vial Reconstitution Chart

The 10mg vial is the second most common research-peptide size for semaglutide. It carries more doses per vial, which suits people who have settled into a maintenance dose and want fewer reconstitutions.

10mg Vial + 2mL BAC Water (5mg/mL): Compact, Higher Concentration

At 5mg/mL every dose fits in a small volume. The trade-off is precision: a starter dose of 0.25mg is only 5 units, so use a 0.3mL or 0.5mL syringe for accurate reading at the low end.

Vial longevity at 5mg/mL: 10mg / 2.4mg is approximately 4 doses; 10mg / 1.0mg = 10 doses; 10mg / 0.5mg = 20 doses.

10mg Vial + 4mL BAC Water (2.5mg/mL): Identical Units to 5mg + 2mL

Adding 4mL to a 10mg vial gives 2.5mg/mL, the same concentration as the 5mg + 2mL setup, so the units are identical. Choose this option if you want the familiar markings of the recommended 5mg chart but more doses per vial, roughly 4 at the 2.4mg maintenance dose versus 2 from a 5mg vial.

Because the concentration matches the 5mg + 2mL setup, there is no syringe-capacity issue at 2.4mg here either: the maintenance dose stays at 96 units.

Semaglutide Titration Schedule: Which Dose Column Are You On?

The tables above have a dose column for every step. This is the FDA-approved Wegovy schedule from the STEP 1 protocol, so you know which column to read this week.

Some prescribers hold patients at a lower dose for longer if side effects are slow to settle. If your protocol differs, follow it and read the matching column. For the full reasoning behind the schedule, see the semaglutide dosing guide. If you are running sub-therapeutic doses, the microdosing reference scales these IU values down proportionally.

Storing Reconstituted Semaglutide

How Many Semaglutide Doses Per Vial, and Will They Stay Stable?

Stability is rarely the limiting factor at standard doses. A 5mg vial at the 0.25mg starter dose lasts 20 doses, which is 20 weeks, comfortably outside any reasonable shelf life, so you would finish a vial in chunks rather than keep one open that long. The same 5mg vial at the 2.4mg maintenance dose is approximately 2 doses, about 2 weeks, well within the window. At no standard dose does a single open vial outlive the 28 to 56 day stability range, so waste is not a concern as long as you label the reconstitution date and inspect before each draw.

Compounded Semaglutide vs Ozempic and Wegovy Pens

This chart applies only to lyophilized, freeze-dried compounded semaglutide powder that you reconstitute yourself. Ozempic and Wegovy are different products entirely. They arrive as prefilled pens with a concentration fixed by Novo Nordisk that varies by pen strength, and they require no mixing. If you are using an Ozempic or Wegovy pen, you do not need this page at all: your dose is simply the number you dial on the pen in milligrams.

Compounded semaglutide contains the same active molecule but is prepared by a compounding pharmacy rather than the brand manufacturer, and it ships as powder precisely because that is the form that needs BAC water. For more on how the two differ and what to verify before sourcing, see the compounded semaglutide overview.

Use the Semaglutide Calculator for Custom Setups

The four tables on this page cover the standard 5mg and 10mg reconstitutions. If your configuration is non-standard, for example a 3mg vial, a 1.5mL water volume, or a dose that falls between titration steps, enter your vial size, your BAC water volume, and your target dose into the free calculator and it returns the exact units instantly.

Semaglutide Reconstitution Video Walkthrough

To see reconstitution demonstrated alongside the unit math in this chart, this walkthrough from a medical group covers the general technique for peptides like semaglutide. Follow your pharmacy's instructions and the linked reconstitution guide for the exact procedure.