Key takeaways
- Units = dose (mg) ÷ concentration (mg/mL) × 100. 0.25 mg at 2.5 mg/mL is 10 units.
- Wegovy’s label steps are 0.25, 0.5, 1, 1.7 and 2.4 mg, 4 weeks each. Since March 2026 the label allows up to 7.2 mg (Wegovy HD).
- Ozempic starts the same way and may go to 1 mg, then 2 mg, each after at least 4 weeks.
- The FDA documented 5 to 20 times overdoses with compounded semaglutide, including 50 units drawn instead of 5.
- Missed-dose windows differ: 5 days for Ozempic, a 2-day rule for Wegovy injection.
How to use the semaglutide calculator
The calculator turns a semaglutide dose in mg into the volume to draw, in mL and in U-100 insulin-syringe units. It keeps your numbers in the page link, so you can share the exact result.
- Semaglutide in the vial (mg). Use the total on the label, such as 2, 3, 5 or 10 mg. If the vial also lists another ingredient, use the peptide blend calculator.
- Bacteriostatic water added (mL). The diluent injected into a powder vial. A liquid vial from a pharmacy already has a concentration printed in mg/mL; enter it as 1 mL and that number of mg.
- Dose per injection. Enter it in mg, exactly as prescribed. The presets match the label steps. The tool does not choose a dose.
- Syringe. Starting doses are often only 5 to 25 units, so a 0.3 or 0.5 mL syringe is easier to read than a 1 mL one.
- Read the result. Draw to the unit mark shown, read the warnings and open Show the math.
What semaglutide is
Semaglutide is a GLP-1 (glucagon-like peptide-1) receptor agonist with 94% sequence homology to the natural hormone. A fatty acid side chain binds it to albumin in the blood, which gives it an elimination half-life of about 1 week. That is why it is injected once weekly, and why the Wegovy label says it stays in the circulation for about 5 to 7 weeks after the last dose.
Novo Nordisk sells it under two FDA-approved names. Ozempic treats type 2 diabetes and lowers cardiovascular and kidney risks in adults with type 2 diabetes and heart or chronic kidney disease. Wegovy injection is approved for weight reduction in adults and children 12 and older, for cardiovascular risk reduction, and for a form of fatty liver disease (MASH) with moderate to advanced fibrosis. Wegovy tablets, a 25 mg once-daily pill, joined the label in December 2025. Compounded and “research” semaglutide are not FDA-approved.
Semaglutide dosage chart: the label schedules
Both labels start at 0.25 mg injected once weekly for 4 weeks, then 0.5 mg. After that they part ways:
- Wegovy steps up every 4 weeks to 1 mg, 1.7 mg and then 2.4 mg, the recommended adult weight-reduction maintenance dose (1.7 mg is the alternative). For adults who tolerate 2.4 mg for at least 4 weeks and need more weight loss, the label allows up to 7.2 mg (Wegovy HD). If a step is not tolerated, the label suggests delaying escalation for 4 weeks.
- Ozempic may increase to 1 mg, then to a 2 mg maximum, each “after at least 4 weeks” if more blood-sugar control is needed. Its maintenance doses are 0.5, 1 or 2 mg.
| Step | Weeks | Wegovy | Ozempic |
|---|---|---|---|
| 1 | 1–4 | 0.25 mg | 0.25 mg |
| 2 | 5–8 | 0.5 mg | 0.5 mg |
| 3 | 9–12 | 1 mg | 1 mg |
| 4 | 13–16 | 1.7 mg | 2 mg |
| 5 | 17 onward | 2.4 mg | stays 2 mg |
| Option | 21 onward | 7.2 mg (HD) | — |
Source: Ozempic and Wegovy prescribing information, section 2. Label weeks are minimums, not a timetable.
Semaglutide dosage chart in units
Compounded and research vials start as powder or as a liquid of a pharmacy’s chosen strength. The FDA’s 2024 alert noted that concentrations vary between compounders, and even within one compounder. This chart converts each label dose into U-100 units at five example concentrations.
| Dose | 1 mg/mL | 2 mg/mL | 2.5 mg/mL | 3 mg/mL | 5 mg/mL |
|---|---|---|---|---|---|
| 0.25 mg | 25 | 12.5 | 10 | 8.33 | 5 |
| 0.5 mg | 50 | 25 | 20 | 16.7 | 10 |
| 1 mg | 100 | 50 | 40 | 33.3 | 20 |
| 1.7 mg | — | 85 | 68 | 56.7 | 34 |
| 2 mg | — | 100 | 80 | 66.7 | 40 |
| 2.4 mg | — | — | 96 | 80 | 48 |
— means more than 100 units, the capacity of a 1 mL syringe. Mixes that give each column:1 mg/mL = 2 mg + 2 mL, 3 mg + 3 mL; 2 mg/mL = 2 mg + 1 mL, 3 mg + 1.5 mL, 5 mg + 2.5 mL; 2.5 mg/mL = 5 mg + 2 mL; 3 mg/mL = 3 mg + 1 mL; 5 mg/mL = 5 mg + 1 mL, 10 mg + 2 mL.
Semaglutide units to mg: the formula
A unit on an insulin syringe is a volume, not an amount of drug. On a U-100 syringe, 1 unit is 0.01 mL. These formulas connect the dose to the mark on the barrel.
Check: 0.25 ÷ 2.5 × 100 = 10 units.
| Term | Meaning | Where to find it |
|---|---|---|
| Vial (mg) | Total semaglutide in the vial | Vial or pharmacy label |
| Water (mL) | Bacteriostatic water added | What you or the pharmacy injected |
| C | Concentration after mixing | Calculated, or printed on a liquid vial |
| Units | U-100 syringe mark (0.01 mL each) | Calculated |
Example 1: 5 mg vial, 2 mL water, 0.25 mg
The concentration is 5 ÷ 2 = 2.5 mg/mL. The volume is 0.25 ÷ 2.5 = 0.1 mL, which is 10 units. The vial holds 20 doses of 0.25 mg.
Example 2: 10 mg vial, 2 mL water, 1 mg
The concentration is 5 mg/mL. The volume is 1 ÷ 5 = 0.2 mL, or 20 units. The vial holds 10 doses of 1 mg.
Example 3: 5 mg vial, 2 mL water, 2.4 mg
At 2.5 mg/mL, 2.4 mg is 0.96 mL, or 96 units. That needs a 1 mL syringe, and the vial holds only 2 full doses.
Example 4: the FDA’s 5-unit error, in mg
At 2.5 mg/mL, 5 units is 0.125 mg. Drawing 50 units instead gives 1.25 mg, ten times the dose. This is the mistake the FDA described. The reverse peptide calculator turns any unit count back into mg, and the mg to units calculator goes the other way.
How much BAC water to add to a semaglutide vial
No water volume is universally correct, and a pharmacy’s instructions come first. Semaglutide doses are small, so the risk is a draw too tiny to read. Aim for your dose to land on a whole mark of at least 5 to 10 units. More water lowers the concentration and makes small doses bigger and easier to see. The BAC water calculator works backward from the units you want.
In the tables, — means the dose is more than the vial holds, and >100 means it will not fit a 1 mL syringe in one draw.
How much BAC water for a 2 mg semaglutide vial?
With 1 mL, a 2 mg vial is 2 mg/mL and 0.25 mg is 12.5 units. With 3 mL it is 0.67 mg/mL and 0.25 mg is 37.5 units. It holds 8 doses of 0.25 mg.
| Water | mg/mL | 0.25 mg | 0.5 mg | 1 mg | 1.7 mg | 2 mg | 2.4 mg |
|---|---|---|---|---|---|---|---|
| 1 mL | 2 | 12.5 | 25 | 50 | 85 | 100 | — |
| 1.5 mL | 1.33 | 18.8 | 37.5 | 75 | >100 | >100 | — |
| 2 mL | 1 | 25 | 50 | 100 | >100 | >100 | — |
| 3 mL | 0.67 | 37.5 | 75 | >100 | >100 | >100 | — |
How much BAC water for a 3 mg semaglutide vial?
With 1 mL, a 3 mg vial is 3 mg/mL and 0.25 mg is 8.33 units. With 3 mL it is 1 mg/mL and 0.25 mg is 25 units. It holds 12 doses of 0.25 mg or 1 of 2.4 mg.
| Water | mg/mL | 0.25 mg | 0.5 mg | 1 mg | 1.7 mg | 2 mg | 2.4 mg |
|---|---|---|---|---|---|---|---|
| 1 mL | 3 | 8.33 | 16.7 | 33.3 | 56.7 | 66.7 | 80 |
| 1.5 mL | 2 | 12.5 | 25 | 50 | 85 | 100 | >100 |
| 2 mL | 1.5 | 16.7 | 33.3 | 66.7 | >100 | >100 | >100 |
| 3 mL | 1 | 25 | 50 | 100 | >100 | >100 | >100 |
How much BAC water for a 5 mg semaglutide vial?
With 1 mL, a 5 mg vial is 5 mg/mL and 0.25 mg is 5 units. With 3 mL it is 1.67 mg/mL and 0.25 mg is 15 units. It holds 20 doses of 0.25 mg or 2 of 2.4 mg.
| Water | mg/mL | 0.25 mg | 0.5 mg | 1 mg | 1.7 mg | 2 mg | 2.4 mg |
|---|---|---|---|---|---|---|---|
| 1 mL | 5 | 5 | 10 | 20 | 34 | 40 | 48 |
| 1.5 mL | 3.33 | 7.5 | 15 | 30 | 51 | 60 | 72 |
| 2 mL | 2.5 | 10 | 20 | 40 | 68 | 80 | 96 |
| 3 mL | 1.67 | 15 | 30 | 60 | >100 | >100 | >100 |
How much BAC water for a 10 mg semaglutide vial?
With 1 mL, a 10 mg vial is 10 mg/mL and 0.25 mg is 2.5 units. With 3 mL it is 3.33 mg/mL and 0.25 mg is 7.5 units. It holds 40 doses of 0.25 mg or 4 of 2.4 mg.
| Water | mg/mL | 0.25 mg | 0.5 mg | 1 mg | 1.7 mg | 2 mg | 2.4 mg |
|---|---|---|---|---|---|---|---|
| 1 mL | 10 | 2.5 | 5 | 10 | 17 | 20 | 24 |
| 1.5 mL | 6.67 | 3.75 | 7.5 | 15 | 25.5 | 30 | 36 |
| 2 mL | 5 | 5 | 10 | 20 | 34 | 40 | 48 |
| 3 mL | 3.33 | 7.5 | 15 | 30 | 51 | 60 | 72 |
Semaglutide vs tirzepatide: units are not interchangeable
It is tempting to carry a unit count over when switching between the two drugs. That is dangerous, because a unit is only a volume. Tirzepatide label doses are far larger in mg (2.5 to 15 mg against 0.25 to 2.4 mg), and each vial has its own strength. The table compares each label step at two example concentrations.
| Weeks | Wegovy dose | Units | Zepbound dose | Units |
|---|---|---|---|---|
| 1–4 | 0.25 mg | 10 | 2.5 mg | 12.5 |
| 5–8 | 0.5 mg | 20 | 5 mg | 25 |
| 9–12 | 1 mg | 40 | 7.5 mg | 37.5 |
| 13–16 | 1.7 mg | 68 | 10 mg | 50 |
| 17–20 | 2.4 mg | 96 | 12.5 mg | 62.5 |
| 21–24 | 2.4 mg | 96 | 15 mg | 75 |
Wegovy reaches its 2.4 mg maintenance dose at week 17; the tirzepatide label has one more step.
At these strengths, 10 units is 0.25 mg of semaglutide but 2 mg of tirzepatide. Always recalculate with the right drug’s page: the tirzepatide calculator or, for the investigational triple agonist, the retatrutide calculator.
Pens, tablets and vials: how branded semaglutide is supplied
Branded semaglutide never needs mixing. The current labels list:
- Ozempic pens: multi-dose pens holding 3 mL: 2 mg/3 mL (0.68 mg/mL) for the 0.25 and 0.5 mg doses, 4 mg/3 mL (1.34 mg/mL) for 1 mg and 8 mg/3 mL (2.68 mg/mL) for 2 mg. Ozempic also comes in single-dose prefilled syringes of 0.25, 0.5 and 1 mg.
- Wegovy injection: single-dose pens and syringes, plus a multi-dose FlexTouch pen. The label says never to share a FlexTouch pen, even with a new needle.
- Wegovy tablets: 1.5, 4, 9 and 25 mg, taken once daily on an empty stomach.
| Presentation | Dose | Volume per dose | mg/mL |
|---|---|---|---|
| Single-dose pen | 0.25 mg | 0.5 mL | 0.5 |
| Single-dose pen | 0.5 mg | 0.5 mL | 1 |
| Single-dose pen | 1 mg | 0.5 mL | 2 |
| Single-dose pen | 1.7 mg | 0.75 mL | 2.27 |
| Single-dose pen | 2.4 mg | 0.75 mL | 3.2 |
| Single-dose pen (Wegovy HD) | 7.2 mg | 0.75 mL | 9.6 |
| FlexTouch pen (4 doses, 9.6 mg / 3 mL) | 2.4 mg | 0.75 mL | 3.2 |
Each branded strength has its own concentration, and the pens deliver set mg doses, not syringe units. None of these numbers carry over to a compounded vial.
Missed a dose? The label rules
Each product has its own rule, so check which one you use.
- Ozempic: take the missed dose as soon as possible within 5 days. After 5 days, skip it and take the next dose on your regular day. You can change your injection day if doses are at least 2 days (more than 48 hours) apart.
- Wegovy injection: if the next dose is more than 2 days away, take the missed dose as soon as possible. If it is less than 2 days away, skip it. After 2 or more missed doses in a row, the label says to restart escalation at a lower dose.
- Wegovy tablets: skip the missed tablet and take the next one the following day.
Compounded products carry no FDA-reviewed missed-dose instructions, so ask your prescriber, especially after several missed weeks.
How to store semaglutide
Both labels say to refrigerate unused product at 2 °C to 8 °C (36 °F to 46 °F), keep it away from the cooling element, and never use it if it has frozen.
- Ozempic pens can be kept for 56 days after first use at 15 °C to 30 °C (59 °F to 86 °F) or in the refrigerator. Store them without a needle attached.
- Wegovy single-dose pens and syringes may be kept at 8 °C to 30 °C (46 °F to 86 °F) for up to 28 days before the cap comes off. Keep them in the carton to protect from light.
- Wegovy FlexTouch can be kept for 56 days after first use, at room temperature or in the refrigerator.
- Compounded vials follow the pharmacy’s label. For multi-dose vials without stability data, USP <797> sets a default 28-day beyond-use date after first puncture (see reconstitution storage).
A 10 mg vial at 0.25 mg a week holds 40 doses, far more than 28 days’ worth. The doses per vial calculator shows which runs out first.
The FDA dosing-error alert and compounding status
On July 26, 2024, the FDA warned about dosing errors with compounded injectable semaglutide sold in multiple-dose vials. It found that:
- Instructions often gave doses in units, whose volume depends on the concentration, rather than in mg or mL.
- Some patients were told to use a 1 mL U-100 syringe for a 5-unit (0.05 mL) dose and drew 50 units instead.
- Some clinicians miscalculated mg-to-unit conversions, leading to 5 to 10 times the intended dose.
- Overall, patients took 5 to 20 times more than intended. Some needed medical care or a hospital stay, with effects including nausea, vomiting, fainting, dehydration, pancreatitis and gallstones.
The shortage that allowed wide compounding is over. The FDA declared the semaglutide shortage resolved on February 21, 2025. Enforcement discretion ended April 22, 2025 for 503A pharmacies (state-licensed, patient-specific) and May 22, 2025 for 503B outsourcing facilities (larger compounders registered with the FDA). A federal court denied a request to block the decision on April 24, 2025.
A 503A pharmacy now may not compound essential copies of Ozempic or Wegovy regularly or in inordinate amounts, unless a prescriber documents a significant difference for an identified patient. Semaglutide is on neither the shortage list nor the 503B bulks list. On April 30, 2026, the FDA proposed formally excluding it from the bulks list; comments closed June 29, 2026, and the final decision was still pending when we last checked. Compounded drugs are not FDA-approved or reviewed for safety, effectiveness or quality. As of May 31, 2026, the FDA had received 990 adverse event reports tied to compounded semaglutide.
Common semaglutide dosing mistakes
- Reading 5 units as 50. On a 1 mL syringe the numbers run 10, 20, 30. Use a 0.3 or 0.5 mL syringe for small doses when you can.
- Reusing a unit count after changing pharmacy. 20 units is 0.5 mg at 2.5 mg/mL but 1 mg at 5 mg/mL.
- Very small draws. 0.25 mg from a 10 mg vial with 1 mL is 2.5 units, which is hard to measure. The calculator warns below 2 units.
- Mixing up mg and mcg. 0.25 mg is 250 mcg. Choose the right unit in the dose box.
- Using a U-40 syringe. Each U-40 unit holds 2.5 times more liquid than a U-100 unit.
- Treating tablet and injection mg as equal. Wegovy tablets use different doses and cannot be converted with this calculator.
Frequently asked questions
How many units is 0.25 mg of semaglutide?
Divide 0.25 mg by the concentration and multiply by 100. At 2.5 mg/mL (a 5 mg vial with 2 mL of water) it is 10 units. At 5 mg/mL it is 5 units, and at 1 mg/mL it is 25 units. The mg to units calculator handles any strength.
How many units is 2.4 mg of semaglutide?
At 2.5 mg/mL, 2.4 mg is 96 units, almost a full 1 mL syringe. At 5 mg/mL it is 48 units. At 1 mg/mL it would be 240 units, more than a 1 mL syringe holds, so it cannot be drawn in one go.
How much bacteriostatic water do I add to 10 mg of semaglutide?
Any volume the vial holds works if you recalculate. With 2 mL a 10 mg vial is 5 mg/mL, and 0.25 mg is only 5 units. With 3 mL it is 3.33 mg/mL and 0.25 mg is 7.5 units. Follow your pharmacy’s instructions if given. The BAC water calculator works backward from the units you want.
How do I convert semaglutide units to mg?
Multiply the units by the concentration in mg/mL and divide by 100. At 2.5 mg/mL, 20 units is 20 × 2.5 ÷ 100 = 0.5 mg. This assumes a U-100 syringe. The reverse peptide calculator does it for any vial and water volume.
What is the semaglutide dosage schedule on the label?
Both labels start at 0.25 mg once weekly for 4 weeks, then 0.5 mg. Wegovy then steps to 1 mg, 1.7 mg and 2.4 mg every 4 weeks, with 2.4 mg the recommended adult weight-loss maintenance dose. Ozempic may go to 1 mg and then 2 mg, each after at least 4 weeks, if more glucose control is needed. Your prescriber sets your dose.
What if I miss a semaglutide dose?
It depends on the product. The Ozempic label allows the dose within 5 days; after that, skip it. The Wegovy injection label says take it if the next dose is more than 2 days away, otherwise skip it, and to restart at a lower dose after 2 or more missed doses in a row. Missed Wegovy tablets are skipped.
Is the 7.2 mg Wegovy dose FDA-approved?
Yes. The FDA approved Wegovy HD, a 7.2 mg single-dose pen, in March 2026. The label allows it for adults using Wegovy for weight reduction who have tolerated 2.4 mg for at least 4 weeks and need more weight loss. It is the maximum Wegovy dose. It is not part of the standard escalation.
Is there a semaglutide pill for weight loss?
Yes. Wegovy tablets were added to the Wegovy label in December 2025. They start at 1.5 mg once daily and step up every 30 days through 4 mg and 9 mg to a 25 mg maintenance dose. Tablet mg are not comparable to injection mg, so never convert between them with this calculator.
Can pharmacies still compound semaglutide?
The FDA declared the semaglutide shortage resolved on February 21, 2025. Grace periods ended April 22, 2025 for 503A pharmacies and May 22, 2025 for 503B outsourcing facilities. A 503A pharmacy may still compound for an individual patient in limited cases, such as a documented clinical difference. Compounded semaglutide is not FDA-approved.
Are semaglutide units the same as tirzepatide units?
No. A unit is 0.01 mL, so the mg depends on each vial. 10 units of a 2.5 mg/mL semaglutide mix is 0.25 mg; 10 units of a 20 mg/mL tirzepatide mix is 2 mg. Use the tirzepatide calculator for tirzepatide.
Sources
We check every formula and figure on this page against primary sources. See our editorial policy for how we review content.
- Ozempic (semaglutide) injection: prescribing information (revised 05/2026)
- Wegovy (semaglutide) injection and tablets: prescribing information (revised 06/2026)
- FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products
- FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize
- FDA proposes to exclude semaglutide, tirzepatide, and liraglutide on 503B bulks list
- FDA approves fourth product under national priority voucher program, higher dose semaglutide
Reviewed by the PeptideConvert Editorial Team
Last reviewed . PeptideConvert tools do arithmetic only. They do not recommend a dose, and nothing on this site is medical advice. Always follow the label and your prescriber. Read the full medical disclaimer.