Semaglutide Dosage Calculator

Semaglutide doses are written in milligrams (mg), a weight of drug. When it comes in a vial, the dose has to become a volume you can draw into a syringe, and that volume depends on how strong your vial is.

What the Semaglutide Dosage Calculator Measures

It measures volume, not dose. You bring the dose your prescriber set and the concentration on your pharmacy label, and it shows the mL and the U-100 syringe mark. It does not suggest, check or change doses.

The Formula

Volume to inject (mL) = prescribed dose (mg) / vial concentration (mg/mL)

Units on a U-100 syringe = volume (mL) x 100

Drug in each unit (mg) = vial concentration (mg/mL) / 100

The "x 100" step works because U-100 means 100 units in each mL, so each unit is 0.01 mL¹.

How This Calculator Computes Your Result

Enter your dose in mg and your vial's concentration in mg/mL. If your prescription is in mcg, divide by 1,000 first (250 mcg = 0.25 mg). If the label gives a total, such as 5 mg in 2 mL, divide the mg by the mL (2.5 mg/mL). Do not enter the total mg in the vial as the concentration.

The result shows mL to 3 decimals and units to 1 decimal, with every step of the math. You get a warning if the volume is more than a 1 mL syringe holds (often a unit mix-up), below 1 unit, between whole-unit marks, or 5 units or fewer, where a 1-unit slip changes the dose by 20% or more. A dose above 7.2 mg, the highest in any FDA-approved semaglutide injection label, is also flagged³. Mixing powder vials and rounding to syringe marks are handled by the Peptide Calculator. For tirzepatide, use the Tirzepatide Dosage Calculator.

What Your Result Means

Your result is the volume that holds your dose in this vial and the mark it reaches on a U-100 syringe. It also shows what one unit holds, which syringe sizes fit, and ten times your volume, so a slipped zero stands out.

Example only: a 0.25 mg dose from a 2.5 mg/mL vial is 0.25 / 2.5 = 0.1 mL, and 0.1 x 100 = 10 units.

A unit is a mark on the syringe, not an amount of drug. The same 10 units holds a different dose in each of these example vials:

So never reuse a number of units from another vial, another person or a website.

Dosing Errors and FDA's Position on Compounded Semaglutide

In July 2024, FDA warned of overdoses with compounded semaglutide in vials, which may be linked to confusion between units of measure and unfamiliarity with vials². Some patients told to draw 5 units (0.05 mL) with a U-100 syringe drew 50 units, and most reports involved 5 to 20 times the intended dose². One provider meant to order 0.25 mg (5 units) but wrote 25 units². Reported effects included nausea, vomiting, pancreatitis and gallstones, and some people needed hospital care². FDA asks compounders to supply a syringe sized for the dose and show patients how to measure it².

Compounded drugs are not FDA-approved⁶. FDA declared the semaglutide shortage, which began in 2022, resolved on February 21, 2025, and held off enforcement until April 22, 2025 for pharmacies and May 22, 2025 for outsourcing facilities⁶. Since then, FDA treats compounded semaglutide as a copy of the approved drug, which limits how often a pharmacy may make it, unless a prescriber documents a significant difference for the patient⁶. FDA knows of no lawful basis for compounding the salt forms semaglutide sodium or acetate⁷. On April 30, 2026, FDA proposed keeping semaglutide off the list of bulk substances outsourcing facilities may compound from, finding no clinical need⁸. FDA said it would consider comments, due by June 29, 2026, before a final decision⁸.

FDA-Approved Semaglutide Dose Schedules

This is label information only, not dosing advice. It covers brand-name products, not compounded semaglutide. Your prescriber sets your dose.

Wegovy injection (once weekly)³

For weight reduction in adults, the label's maintenance dosage is 1.7 mg or 2.4 mg (recommended)³. If 2.4 mg is tolerated for at least 4 weeks and more weight reduction is clinically indicated, it may be raised to a maximum of 7.2 mg once weekly³.

Wegovy tablets (once daily): 1.5 mg on days 1 through 30, 4 mg on days 31 through 60, 9 mg on days 61 through 90, then 25 mg from day 91³.

Ozempic injection (type 2 diabetes): 0.25 mg once weekly for 4 weeks, then 0.5 mg⁴. If more glucose control is needed, it may go to 1 mg and then 2 mg, each after at least 4 weeks on the dose before, with 2 mg once weekly as the maximum⁴.

Rybelsus and Ozempic tablets (type 2 diabetes, once daily): Rybelsus starts at 3 mg, then 7 mg, then 14 mg if needed. Ozempic tablets start at 1.5 mg, then 4 mg, then 9 mg if needed⁵. The label says they are not substitutable mg for mg⁵.

Why Pen and Tablet Users Do Not Need This Conversion

FDA-approved semaglutide injections are dosed in mg, in standard strengths². Wegovy comes in single-dose pens and syringes that each give one set dose, plus a FlexTouch pen that delivers four 2.4 mg doses³. Ozempic pens are listed by the dose each injection gives, and its single-dose syringes each hold one 0.25 mg, 0.5 mg or 1 mg dose⁴. The label says the 0.25 mg or 0.5 mg pen delivers doses in 0.25 mg or 0.5 mg increments only⁴. Tablets are whole, fixed strengths⁵. Nothing is measured in mL or units, so this tool is only for liquid drawn from a vial with a syringe.