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Semaglutide Dosage Calculator (mg to Units)

Enter the dose on your prescription and the strength of your compounded semaglutide vial, and the calculator returns the volume to draw and the units on a U-100 insulin syringe. It is the conversion the FDA has warned goes wrong most often with vial-based semaglutide, with the label's escalation schedule shown as information only.

  • Calculator
  • About 4 min
  • Dose volume arithmetic (Boyer, Math for Nurses)
  • Runs in your browser, nothing is sent
  • Medical review: Medical review pending
Open the calculator

What this calculator works out

Brand-name semaglutide pens deliver a fixed dose with a click; compounded semaglutide comes in a vial labeled in milligrams per milliliter and is drawn into an insulin syringe marked in units. Converting one into the other is simple arithmetic, and getting it wrong by one decimal place has put people in hospital. This page does the conversion and shows the steps.

  1. 1

    Units on a U-100 syringe

    The headline number: the prescribed milligrams divided by the vial's mg/mL strength gives milliliters, and milliliters times 100 gives units on a U-100 insulin syringe. A 0.25 mg dose from a 2.5 mg/mL vial is 0.1 mL, or 10 units.

  2. 2

    Volume in mL and the vial's concentration

    Both intermediate numbers are shown so you can check them against the pharmacy label and the syringe markings, and so an error in one input is visible rather than hidden in the final figure.

  3. 3

    A sanity check against known errors

    The FDA's July 2024 alert described patients drawing five to ten times the intended dose after confusing milligrams, milliliters and units. The result bands flag draws that are too small to measure or larger than one syringe, the two patterns behind most of those reports.

How this compares with a typical online quiz

FeatureTypical free quizRegenerated.com
Dose entered by you from a prescriptionOften pre-filled with a doseAlways yours; no default and no suggested number
Vial strength handled as mg/mLSometimesYes: enter the total mg and mL on the label, or the mg/mL and 1 mL
Escalation scheduleShown as a plan to followShown as label information; the prescription is the only dose used
FDA dosing-error alert explainedRarelyYes, with the common error patterns
Sells or links to semaglutideOftenNever
Answers sent to a serverOftenNever; scored in your browser, counts-only events

Why mg, mL and units get confused

A compounded semaglutide vial carries three numbers that look alike: the total milligrams of drug in the vial, the milliliters of liquid, and the concentration in milligrams per milliliter. A prescription adds a fourth, the dose in milligrams, and the syringe adds a fifth, units. A U-100 insulin syringe is marked so that 100 units equal 1 mL, which means units say nothing about milligrams until you know the concentration. The same 10 units is 0.25 mg from a 2.5 mg/mL vial and 0.5 mg from a 5 mg/mL vial.

On July 26, 2024 the FDA issued a compounding risk alert after receiving reports of adverse events, some needing hospital care, from dosing errors with compounded injectable semaglutide. The errors came from two directions: patients unfamiliar with drawing from a vial confused units, milliliters and milligrams, and some clinicians miscalculated the conversion, with patients receiving five to ten times the intended dose. Symptoms reported included severe nausea, vomiting, dehydration and low blood sugar. The FDA's advice was for prescribers to write the dose in milligrams and the volume in both milliliters and units, and for patients to confirm with the pharmacist how to measure the dose before the first injection.

This calculator exists to make that confirmation easy to repeat at home. It does not replace the pharmacist's instruction; it lets you check that your understanding of the vial matches the numbers.

Compounded semaglutide and where it stands

Semaglutide is the active ingredient in Ozempic, Wegovy and Rybelsus, which are FDA-approved products with fixed-dose pens or tablets. Compounded semaglutide is prepared by a pharmacy from the bulk substance, usually as a multi-dose vial in a strength such as 2.5 mg/mL or 5 mg/mL, and is not FDA-approved or reviewed for safety, effectiveness or quality. Pharmacies were permitted to compound it while the brand products were on the FDA's drug shortage list. The FDA declared that shortage resolved on February 21, 2025; the period in which it would not act against a state-licensed pharmacy compounding semaglutide ended on April 22, 2025, and the period for outsourcing facilities ended on May 22, 2025. The FDA's page for compounders, current as of April 1, 2026 and checked on October 8, 2026, states that semaglutide appears neither on the 503B bulks list nor on the drug shortage list, and on April 30, 2026 the agency proposed to exclude semaglutide, tirzepatide and liraglutide from the 503B bulks list, finding no clinical need for outsourcing facilities to compound them from bulk. That is a proposal, with comments taken to June 29, 2026, and not a final rule; as of October 8, 2026 the FDA had not issued a final determination. What is left is narrow and patient-specific, such as a prescriber's documented determination that a compounded product has a significant difference from the commercially available one for an identified individual patient. Whether a given vial qualifies does not follow from the lists alone, so ask the pharmacy on what basis yours was compounded. Some clinics still offer compounded semaglutide under those narrower conditions.

Whatever the source, the arithmetic on this page is the same. What changes with a compounded product is that the concentration can differ between pharmacies and between batches, so the vial label, not memory of the last vial, is the input to use every time.

Methodology and sources

The calculator applies the standard dimensional analysis taught for injectable drugs supplied as a solution, as in Boyer's Math for Nurses (9th edition, Wolters Kluwer, 2016): volume to draw equals the prescribed dose divided by the concentration. It is not specific to semaglutide, any population or any indication; it is the same arithmetic used for insulin, heparin or any mg/mL vial. Its limits are practical. It assumes the label is accurate and the solution is uniform, that a U-100 insulin syringe is used (100 units in 1 mL), and that the dose is written in milligrams. It has no way of checking whether the dose is appropriate for you, and no way of knowing the actual content of a compounded vial. If you use a brand pen, this page does not apply: the pen delivers its labeled dose and no conversion is needed.

The arithmetic runs in three steps. Concentration in mg/mL equals the milligrams in the vial divided by its milliliters. Volume in mL equals the prescribed milligrams divided by that concentration. Units on a U-100 syringe equal milliliters times 100. Worked example from the formula registry: 100 mg prescribed from a vial holding 2,000 mg in 10 mL is 200 mg/mL, so 100 / 200 = 0.5 mL, which is 50 units. For semaglutide the numbers are smaller: a 0.25 mg dose from a vial labeled 2.5 mg/mL (5 mg in 2 mL) is 0.25 / 2.5 = 0.1 mL, or 10 units; the same 0.25 mg from a 5 mg/mL vial is 0.05 mL, or 5 units. A 1 mg dose from the 2.5 mg/mL vial is 0.4 mL, or 40 units.

The bands on this page concern measurability only. Under about 2 units the markings on a standard insulin syringe are too coarse to measure reliably, and over 100 units the dose exceeds a 1 mL syringe; both are prompts to check the inputs with the pharmacist, never to change the dose. The escalation steps mentioned in the FAQ are taken from the Wegovy and Ozempic prescribing information as published by the manufacturer and are shown for orientation; the prescription is the only dose the calculator uses.

Medical review: Medical review pending. Last updated .

References

  1. Boyer MJ. Math for Nurses: A Pocket Guide to Dosage Calculation and Drug Preparation. 9th ed. Philadelphia: Wolters Kluwer; 2016. ISBN 9781496303417
  2. US Food and Drug Administration. FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products. Compounding risk alert, July 26, 2024; page content current as of August 27, 2026, checked October 8, 2026. https://www.fda.gov/drugs/human-drug-compounding/compounding-risk-alerts
  3. Novo Nordisk. Wegovy (semaglutide) injection: highlights of prescribing information. US label, section 2, dosage and administration. https://www.novo-pi.com/wegovy.pdf
  4. Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity. N Engl J Med. 2021;384(11):989-1002. doi:10.1056/NEJMoa2032183
  5. US Food and Drug Administration. FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize (content current as of April 1, 2026) and FDA proposes to exclude semaglutide, tirzepatide and liraglutide on the 503B bulks list (April 30, 2026). Checked October 8, 2026. https://www.fda.gov/drugs/drug-alerts-and-statements/fda-clarifies-policies-compounders-national-glp-1-supply-begins-stabilize and https://www.fda.gov/news-events/press-announcements/fda-proposes-exclude-semaglutide-tirzepatide-and-liraglutide-503b-bulks-list

Semaglutide Dosage Calculator (mg to Units) FAQ

Enter 2.5 for the milligrams and 1 for the milliliters; the calculator divides one by the other, so 2.5 mg in 1 mL gives the same concentration as 5 mg in 2 mL. If the label gives both the total milligrams and the total milliliters, enter those as printed and the result is identical.

For information only: the Wegovy prescribing information begins at 0.25 mg once weekly for four weeks, then 0.5 mg, 1 mg and 1.7 mg for four weeks each, reaching a 2.4 mg weekly maintenance dose at week 17, with the option to pause escalation if a step is not tolerated. The Ozempic label for type 2 diabetes runs 0.25 mg, 0.5 mg, 1 mg and 2 mg with at least four weeks at each step. Compounded prescriptions often follow a similar ladder but are set by the prescriber, and a step on the label is not an instruction to change your own dose. Enter whatever your current prescription says.

One of the inputs differs, almost always the concentration. A 0.5 mg dose is 20 units from a 2.5 mg/mL vial and 10 units from a 5 mg/mL vial. Check the strength printed on your vial, not the one on a previous vial or an instruction sheet written for a different batch, and call the pharmacy if the two still disagree. Do not inject until they match.

Not directly. A lyophilized vial needs the diluent volume in the calculation, because the concentration depends on how much water goes in. Use our peptide reconstitution calculator for that case; this page is for vials that arrive as a ready solution with a mg/mL strength on the label.

Yes, as long as it is a U-100 syringe. The unit markings mean the same thing on every U-100 size; a 0.3 mL syringe simply tops out at 30 units and has finer markings, which makes small doses easier to read. Do not use a U-40 or U-500 syringe, or a tuberculin syringe marked only in mL, without the pharmacist showing you the equivalent, because the unit markings differ.

Yes. Your answers and the numbers you enter are scored in your browser and are never sent to us. They stay in this browser tab so you can return to your result, and closing the tab clears them. The only thing the page sends us is a counts-only event: which test was started or completed, the result band and the headline number, with no answers, no entered values and no account. There is nothing to sign up for.

Talk to a clinic that writes the dose in mg, mL and units

Browse US clinics offering peptide and GLP-1 programs. Look for a prescribing physician, a licensed pharmacy, written instructions that give the dose in milligrams with the units and milliliters alongside, and a plan for reviewing side effects before each step. A listing on Regenerated.com is not an endorsement.

Browse peptide and GLP-1 clinics

A listing is not a treatment endorsement. Read each clinic's published checks and talk to your clinician before starting any treatment.

Important: This calculator is arithmetic for a dose a clinician prescribed. It is not a diagnosis, not a dose suggestion and not a treatment recommendation, and it cannot tell you whether semaglutide or any dose of it is right for you. The prescriber and the dispensing pharmacist are the only people who can confirm what you should draw up. If your symptoms are severe or sudden, seek urgent medical care.