How the Semaglutide calculator works
Licensed products are pre-filled pens. Vials are either a ready-mixed solution labelled with a concentration in mg/mL, or a lyophilized powder labelled in milligrams. The quick-fill buttons in the calculator are the vial sizes Semaglutide is commonly labelled in (2 mg, 5 mg and 10 mg). If yours is different, type it in.
Amounts of Semaglutide are usually written in milligrams (mg), so the calculator opens in mg.
If your vial is a ready-mixed solution, nothing is reconstituted. Enter any vial size and water volume that give the labelled concentration, for example 2.5 mg and 1 mL for a 2.5 mg/mL solution.
For a field-by-field walkthrough and a guide to syringe types, see the main peptide calculator.
Semaglutide concentration table
Each labelled vial size at the same three round water volumes used across this site. It shows how the arithmetic behaves and is not a suggestion of what to use.
| Vial | Water added | Concentration | Each mark holds |
|---|---|---|---|
| 2 mg vial | 1 mL | 2 mg/mL | 0.2 mg per 10 units |
| 2 mg vial | 2 mL | 1 mg/mL | 0.1 mg per 10 units |
| 2 mg vial | 3 mL | 0.67 mg/mL | 0.067 mg per 10 units |
| 5 mg vial | 1 mL | 5 mg/mL | 0.5 mg per 10 units |
| 5 mg vial | 2 mL | 2.5 mg/mL | 0.25 mg per 10 units |
| 5 mg vial | 3 mL | 1.67 mg/mL | 0.167 mg per 10 units |
| 10 mg vial | 1 mL | 10 mg/mL | 1 mg per 10 units |
| 10 mg vial | 2 mL | 5 mg/mL | 0.5 mg per 10 units |
| 10 mg vial | 3 mL | 3.33 mg/mL | 0.333 mg per 10 units |
Every row for a given vial holds the same total. To compare volumes for a specific reading, use the BAC water calculator.
The formula, step by step
The “Try example numbers” button uses one fixed rule on every page: the smallest labelled vial, 2 mL of water, and whatever amount lands on the 10-unit mark. The amount is a by-product of that rule and not a typical or suggested Semaglutide dose.
- Concentration: 2 mg ÷ 2 mL = 1 mg/mL.
- The 10-unit mark is 10 ÷ 100 = 0.1 mL, which holds 0.1 × 1 = 0.1 mg.
- Run it forwards to check: 0.1 mg ÷ 1 mg/mL = 0.1 mL, and 0.1 × 100 = 10 units.
Semaglutide: general reference
General educational reference for research purposes only. None of it is a recommendation, none of it is medical advice, and none of it is used by the calculator, which works only on the numbers you enter.
Semaglutide is a GLP-1 receptor agonist developed by Novo Nordisk. It is an approved prescription medicine, sold as Ozempic and Wegovy (injections in pre-filled pens) and as Rybelsus (a tablet).
Semaglutide is 94 percent identical in sequence to human GLP-1. Two changes make it long-lasting: an amino-acid substitution that protects it from the enzyme DPP-4, and a fatty-acid side chain that lets it bind to albumin in the blood.
The FDA first approved it in December 2017 as Ozempic, followed by the tablet Rybelsus in September 2019 and Wegovy in June 2021.
- Class
- GLP-1 receptor agonist, approved medicine
- Group
- GLP-1 family
- Also known as
- Ozempic, Wegovy, Rybelsus
- Molecular weight
- About 4,114 Da
- Half-life
- About 1 week. The FDA-approved prescribing information gives an elimination half-life of approximately one week, which is long for a peptide.
- Regulatory status
- Approved medicine. Semaglutide is approved by the FDA and the EMA as a prescription medicine. The licensed injections come in pre-filled pens that measure each dose mechanically, so they need no reconstitution and no calculator. Compounded semaglutide in multi-dose vials spread during the 2022 to 2025 shortage. The FDA declared that shortage resolved in February 2025, and compounding is now limited to narrow, patient-specific cases.
- Labelled vial sizes
- 2 mg, 5 mg and 10 mg
Arithmetic slips to watch for with Semaglutide
Units are not milligrams
On a U-100 syringe, units measure volume: 1 unit is 0.01 mL. How many milligrams sit in that volume depends entirely on the concentration. The same 10 units holds 0.1 mg at 1 mg/mL, 0.25 mg at 2.5 mg/mL and 0.5 mg at 5 mg/mL.
A unit count does not transfer between vials
A number of units copied from another person, another pharmacy or a previous vial is only correct for the concentration it was worked out for. Check the concentration printed on every new vial.
Ready-mixed vials skip the first step
If the label already states a concentration in mg/mL, there is no reconstitution to do. The only arithmetic left is dose ÷ concentration = volume, then volume × 100 = units.
Decimal places matter
Semaglutide amounts are written in milligrams with decimals, so a misplaced decimal point changes the amount by ten times. The “Show the math” panel prints every step, which makes a slipped decimal easy to spot.
What this page does not do
The calculator performs mathematical conversions only. It does not recommend, suggest or verify any Semaglutide dose or schedule, it does not say how much water to add, and it does not say what Semaglutide is for, whether it is safe, or whether it is legal where you live. It is not medical advice, diagnosis or treatment, and Peptrack does not sell, supply or endorse any substance.
Always confirm measurements with a licensed healthcare provider or pharmacist. See the full disclaimer.
Ozempic, Wegovy and Rybelsus are trademarks of Novo Nordisk. Peptrack is not affiliated with, or endorsed by, Novo Nordisk or any other manufacturer.
Sources
- FDA (July 2024): dosing errors associated with compounded injectable semaglutide
- FDA: policies for compounders as national GLP-1 supply stabilizes
- Ozempic (semaglutide) prescribing information, FDA
Facts last checked: September 2026. Regulatory status changes, so check the regulator’s own pages for the current position.
