Semaglutide dose steps are small (a starting dose is a fraction of a millilitre at most concentrations) which makes the reconstitution arithmetic matter more here than almost anywhere else. This runs the whole chain using the numbers you enter.
Reconstitution calculator
Enter the vial as labelled and the bacteriostatic water you actually added. Numbers, dates and choices you enter in this tool are not saved or sent. Page analytics, described on our Privacy page, record page views and clicks but not what you type or select.
Enter the dose exactly as your prescriber wrote it. The calculator does not suggest or pre-fill dose steps.
How to Use This Calculator
The vial, the water, your step, your syringe.
Enter the vial strengthThe milligram figure on the vial before reconstitution: commonly 2 mg, 5 mg or 10 mg.
Enter the bacteriostatic water you addedIn mL. Record it against the vial; it is the number the rest of the math hangs on.
Enter your doseThe amount your prescriber gave you, in mg.
Match your syringeCheck the barrel rating. U-100 and U-40 syringes read identical volumes differently.
How the Math Works
Four steps, all plain arithmetic.
Concentration. Vial strength divided by the volume of bacteriostatic water you added, in mg/mL. Every number below depends on this one, and it changes if you reconstitute the next vial differently. Standard reconstitution arithmetic.
Draw volume. Your dose divided by the concentration, in mL.
Syringe reading. Draw volume multiplied by the syringe's units-per-mL rating. A U-100 and a U-40 syringe give different readings for an identical volume. Check what is printed on the barrel. ISO 7864 syringe graduation standards.
Doses per vial. Vial strength divided by your dose. A larger dose means fewer doses per vial, which is also why cost per dose rises. See the Cost Planner.
Why small doses need more care
The specific risk with semaglutide rather than generic advice.
Small doses are very small volumes. At a high concentration, a small dose can be only a few units on a U-100 syringe, so misreading by two units can be a large percentage error. Choosing a diluent volume that puts your draw in a comfortably readable range is worth doing deliberately, with your prescriber or pharmacist.
Products differ. Semaglutide products and indications have different labeled schedules. Which applies to you is your prescriber's call; see the official prescribing information for your product.
Arithmetic only, not medical advice. This calculator divides numbers you enter. It does not recommend a dose, a diluent volume, a syringe, or a product, and it cannot verify what is actually in your vial. Your prescriber sets your actual dose and schedule. Peptide Plug does not sell, supply or source any compound.
Frequently Asked Questions
How much bacteriostatic water should I use for semaglutide?
That is a decision for you and your prescriber or pharmacist. The calculator works with whatever volume you actually added. As a practical matter, a volume that puts your draw in a comfortably readable range on your syringe is easier to reproduce accurately week to week.
Does this calculator include the labelled dose steps?
No. Enter each dose your prescriber gives you. For the approved dosing schedule, see the official prescribing information for your product.
Why does a small dose need more diluent, not less?
More diluent lowers the concentration, so the same dose becomes a larger volume, and a larger volume is easier to measure accurately on a syringe. The dose is unchanged; only the readability improves.
Is compounded semaglutide the same as the approved product?
No. Compounded and research-grade semaglutide is not the approved product, and that distinction matters. Our semaglutide reference page covers the regulatory position.
How many doses are in my vial?
Vial strength divided by your dose, shown above. Expect slightly fewer in practice because of residual volume, drawing waste and the discard window.
Does the syringe type really change the dose?
It changes the number you read, not the volume you draw. But if you read a U-40 syringe as though it were U-100 you will draw the wrong volume, and the error is more than double.
Does Peptide Plug sell semaglutide?
No. We do not sell, supply, source or link to vendors for any compound. Peptide Plug is a tracking and calculation tool only.
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Tracking tool, not medical advice. Peptide Plug is an organization and calculation tool for adults 18 and older. It does not provide medical advice, diagnosis or treatment, and it does not recommend, suggest or verify any substance, amount, schedule or route. Calculators only perform arithmetic on the numbers you enter; double-check every result. Many compounds referenced on this site are not FDA-approved for human use, and products sold outside an approved supply chain are not verified for identity, purity or concentration. Peptide Plug does not sell, supply, source or link to sellers of any compound. Confirm every decision with a licensed clinician or pharmacist. In an emergency, call 911.
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