How many units is 0.25 mg of semaglutide?

It depends entirely on the concentration, which is why there is no single answer. At 1 mg/mL, 0.25 mg is 25 units. At 2 mg/mL it is 12.5 units, at 2.5 mg/mL it is 10 units, at 5 mg/mL it is 5 units and at 10 mg/mL it is only 2.5 units. Read the concentration off your vial label or work it out from the vial strength and the water added before you draw anything.

How do I convert semaglutide mg to units?

Multiply the dose in mg by 100 and divide by the concentration in mg/mL. The 100 comes from the definition of a U-100 syringe: 100 units is 1 mL. So 0.5 mg at 2.5 mg/mL is 0.5 × 100 ÷ 2.5 = 20 units. To go the other way, multiply the units by the concentration and divide by 100: 20 units at 2.5 mg/mL is 0.5 mg.

How much bacteriostatic water do I add to a 5 mg semaglutide vial?

Whatever your prescriber or compounding pharmacy specified — the volume is part of the prescription, not a free choice, because it sets the concentration every subsequent dose is measured against. For reference, 5 mg with 1 mL of water gives 5 mg/mL and a 0.25 mg dose becomes 5 units; the same vial with 2 mL gives 2.5 mg/mL and the same dose becomes 10 units. Never guess the volume and never reconstitute to a concentration nobody told you to use.

Is 0.25 mg the same as 250 mcg of semaglutide?

Yes. There are 1,000 micrograms in a milligram, so 0.25 mg is 250 mcg, 0.5 mg is 500 mcg, 1.7 mg is 1,700 mcg and 2.4 mg is 2,400 mcg. Compounded prescriptions are written both ways, which is itself a source of confusion — convert to one unit and stay in it for the whole calculation.

What is the approved semaglutide dose escalation schedule?

Table 1 of the Wegovy injection label gives 0.25 mg once weekly for weeks 1 through 4, then 0.5 mg for weeks 5 through 8, 1 mg for weeks 9 through 12, 1.7 mg for weeks 13 through 16, and a maintenance dose of 2.4 mg or 1.7 mg from week 17. Ozempic starts at 0.25 mg for 4 weeks, then 0.5 mg, with increases to 1 mg and a maximum of 2 mg permitted after at least 4 weeks at the preceding dose. Compounded products are not FDA-approved and their schedules are set by the prescriber.

Why do two people on the same semaglutide dose draw different numbers of units?

Because they have different concentrations in the vial. A man with a 10 mg vial in 1 mL of water draws 0.5 mg as 5 units; a man with a 2 mg vial in 2 mL of water draws the identical 0.5 mg as 50 units. Ten times the marks, the same drug. Never copy a unit count from a forum, a friend or a previous vial — recalculate from your own concentration every time the vial changes.

Can I use a normal syringe instead of a U-100 insulin syringe?

Only if you convert correctly. A U-100 insulin syringe is marked in units where 100 units is 1 mL; a standard 1 mL tuberculin syringe is marked in millilitres, so 0.1 mL on that barrel is the same volume as 10 units on the insulin one. Mixing the two scales up is one of the routes to a ten-fold error, so use whichever syringe your prescriber specified and read the scale it is actually printed with.

How many doses are in a semaglutide vial?

Divide the vial strength by the dose: the water volume changes the units you draw but not how much drug is in the vial. A 5 mg vial gives 20 whole doses at 0.25 mg, 10 at 0.5 mg and 2 at 2.4 mg. A 10 mg vial gives 4 whole doses at 2.4 mg. Discard any remainder that is smaller than a full dose rather than rounding up the draw, and follow the beyond-use date your pharmacy printed on the label.

Free dosing tool

Semaglutide units converter

Convert a prescribed semaglutide dose between milligrams, micrograms and insulin syringe units at your own reconstituted concentration — with the full chart below.

Reviewed by: Alpha Health Finder Editorial Team
Last reviewed: September 2026

Why “units” means nothing without the concentration

A U-100 insulin syringe is graduated so that 100 units is one millilitre. It measures volume, not drug. The syringe has no idea what is in it, so the same 12.5-unit mark delivers 0.125 mg from a vial reconstituted to 1 mg/mL and 1.25 mg from one reconstituted to 10 mg/mL — a ten-fold difference off an identical-looking draw.

Branded semaglutide sidesteps this entirely: an Ozempic or Wegovy pen is a solution at a fixed strength and dials the dose itself. Compounded semaglutide does not. It arrives as a lyophilised powder — commonly 2 mg, 5 mg, 10 mg or 15 mg in the vial — and the concentration is created at the point the bacteriostatic water is added. Divide the vial strength by the volume of water and you have your mg/mL. Nothing else about the product tells you.

That missing step is a documented source of real harm. A poison-control case series of compounded semaglutide reported two patients who self-administered ten-fold dosing errors, and one who was dosing "in millilitres and units rather than in milligrams". The FDA has received multiple adverse event reports, some requiring hospitalisation, that may relate to dosing errors with compounded injectable semaglutide. The converter below exists to make one specific arithmetic mistake harder to make.

The formula

concentration (mg/mL) = vial strength (mg) ÷ bacteriostatic water (mL)

volume (mL) = dose (mg) ÷ concentration (mg/mL)

units (U-100) = volume (mL) × 100

units = dose (mg) × 100 ÷ concentration (mg/mL)

dose (mg) = units × concentration (mg/mL) ÷ 100

The 100 is not a fudge factor — it is the definition of U-100: the barrel is graduated so 100 units is exactly 1 mL. Doses written in micrograms convert first: 250 mcg is 0.25 mg.

Worked example

A 5 mg vial of compounded semaglutide reconstituted with 2 mL of bacteriostatic water, prescribed dose 0.25 mg:

Concentration = 5 mg ÷ 2 mL = 2.5 mg/mL
Volume = 0.25 mg ÷ 2.5 mg/mL = 0.1 mL
Units = 0.1 mL × 100 = 10 units on a U-100 syringe
Each single unit mark delivers 0.025 mg (25 mcg)
At 0.25 mg the 5 mg vial holds 20 whole doses

Semaglutide mg to units chart

Units on a U-100 insulin syringe for each dose, at each reconstituted concentration. Find your concentration across the top, your prescribed dose down the side.

Dose	1 mg/mL2 mg + 2 mL	2 mg/mL2 mg + 1 mL	2.5 mg/mL5 mg + 2 mL	5 mg/mL5 mg + 1 mL	10 mg/mL10 mg + 1 mL
0.125 mg125 mcg	12.5 u0.125 mL	6.25 u0.063 mL	5 u0.05 mL	2.5 u0.025 mL	1.25 u0.013 mL
0.25 mg250 mcg	25 u0.25 mL	12.5 u0.125 mL	10 u0.1 mL	5 u0.05 mL	2.5 u0.025 mL
0.5 mg500 mcg	50 u0.5 mL	25 u0.25 mL	20 u0.2 mL	10 u0.1 mL	5 u0.05 mL
0.75 mg750 mcg	75 u0.75 mL	37.5 u0.375 mL	30 u0.3 mL	15 u0.15 mL	7.5 u0.075 mL
1 mg1000 mcg	100 u1 mL	50 u0.5 mL	40 u0.4 mL	20 u0.2 mL	10 u0.1 mL
1.25 mg1250 mcg	125 u1.25 mL — over one syringe	62.5 u0.625 mL	50 u0.5 mL	25 u0.25 mL	12.5 u0.125 mL
1.7 mg1700 mcg	170 u1.7 mL — over one syringe	85 u0.85 mL	68 u0.68 mL	34 u0.34 mL	17 u0.17 mL
2 mg2000 mcg	200 u2 mL — over one syringe	100 u1 mL	80 u0.8 mL	40 u0.4 mL	20 u0.2 mL
2.4 mg2400 mcg	240 u2.4 mL — over one syringe	120 u1.2 mL — over one syringe	96 u0.96 mL	48 u0.48 mL	24 u0.24 mL
3 mg3000 mcg	300 u3 mL — over one syringe	150 u1.5 mL — over one syringe	120 u1.2 mL — over one syringe	60 u0.6 mL	30 u0.3 mL
7.2 mg7200 mcg	720 u7.2 mL — over one syringe	360 u3.6 mL — over one syringe	288 u2.88 mL — over one syringe	144 u1.44 mL — over one syringe	72 u0.72 mL

Rounded to the quarter-unit mark — the finest split anyone can judge between two printed lines, rather than a graduation any barrel actually carries. A draw above 100 units does not fit in a single 1 mL syringe — that is a signal the vial is too dilute for the dose, not an instruction to inject twice.

Semaglutide reconstitution chart — vial strength × bacteriostatic water

The concentration each combination produces, and what the 0.25 mg starting dose becomes on the syringe at that concentration.

Vial	1 mL water	2 mL water	3 mL water	5 mL water
2 mg2000 mcg powder	2 mg/mL0.25 mg = 12.5 u	1 mg/mL0.25 mg = 25 u	0.667 mg/mL0.25 mg = 37.5 u	0.4 mg/mL0.25 mg = 62.5 u
5 mg5000 mcg powder	5 mg/mL0.25 mg = 5 u	2.5 mg/mL0.25 mg = 10 u	1.667 mg/mL0.25 mg = 15 u	1 mg/mL0.25 mg = 25 u
10 mg10000 mcg powder	10 mg/mL0.25 mg = 2.5 u	5 mg/mL0.25 mg = 5 u	3.333 mg/mL0.25 mg = 7.5 u	2 mg/mL0.25 mg = 12.5 u
15 mg15000 mcg powder	15 mg/mL0.25 mg = 1.75 u	7.5 mg/mL0.25 mg = 3.25 u	5 mg/mL0.25 mg = 5 u	3 mg/mL0.25 mg = 8.25 u

The powder adds negligible volume, so the reconstituted volume is taken as the water added. At the strongest concentrations the quarter-unit resolution of the syringe starts to matter: 0.25 mg at 15 mg/mL is 1.67 units, which can only be drawn as 1.75. A more dilute vial measures a small dose more accurately.

Label dose escalation in syringe units

The FDA-approved Wegovy injection escalation, converted to U-100 units at four common compounded concentrations. Shown so you can check a conversion against the approved schedule.

Stage	2 mg/mL	2.5 mg/mL	5 mg/mL	10 mg/mL
Weeks 1–40.25 mg · 250 mcg	12.5 u0.125 mL	10 u0.1 mL	5 u0.05 mL	2.5 u0.025 mL
Weeks 5–80.5 mg · 500 mcg	25 u0.25 mL	20 u0.2 mL	10 u0.1 mL	5 u0.05 mL
Weeks 9–121 mg · 1000 mcg	50 u0.5 mL	40 u0.4 mL	20 u0.2 mL	10 u0.1 mL
Weeks 13–161.7 mg · 1700 mcg	85 u0.85 mL	68 u0.68 mL	34 u0.34 mL	17 u0.17 mL
Week 17 onward2.4 mg · 2400 mcg	120 u1.2 mL — over one syringe	96 u0.96 mL	48 u0.48 mL	24 u0.24 mL

Table 1 of the Wegovy injection label: 0.25 mg weekly for weeks 1–4, then 0.5 mg, 1 mg and 1.7 mg at four-week intervals, with a maintenance dose of 2.4 mg (or 1.7 mg) from week 17. The label permits escalation to a maximum of 7.2 mg once weekly in adults who have tolerated 2.4 mg for at least four weeks. Ozempic for glycaemic control follows 0.25 mg, 0.5 mg, 1 mg and a maximum of 2 mg. Your prescription governs; this is a reference, not a plan.

Frequently asked questions

How many units is 0.25 mg of semaglutide?: It depends entirely on the concentration, which is why there is no single answer. At 1 mg/mL, 0.25 mg is 25 units. At 2 mg/mL it is 12.5 units, at 2.5 mg/mL it is 10 units, at 5 mg/mL it is 5 units and at 10 mg/mL it is only 2.5 units. Read the concentration off your vial label or work it out from the vial strength and the water added before you draw anything.
How do I convert semaglutide mg to units?: Multiply the dose in mg by 100 and divide by the concentration in mg/mL. The 100 comes from the definition of a U-100 syringe: 100 units is 1 mL. So 0.5 mg at 2.5 mg/mL is 0.5 × 100 ÷ 2.5 = 20 units. To go the other way, multiply the units by the concentration and divide by 100: 20 units at 2.5 mg/mL is 0.5 mg.
How much bacteriostatic water do I add to a 5 mg semaglutide vial?: Whatever your prescriber or compounding pharmacy specified — the volume is part of the prescription, not a free choice, because it sets the concentration every subsequent dose is measured against. For reference, 5 mg with 1 mL of water gives 5 mg/mL and a 0.25 mg dose becomes 5 units; the same vial with 2 mL gives 2.5 mg/mL and the same dose becomes 10 units. Never guess the volume and never reconstitute to a concentration nobody told you to use.
Is 0.25 mg the same as 250 mcg of semaglutide?: Yes. There are 1,000 micrograms in a milligram, so 0.25 mg is 250 mcg, 0.5 mg is 500 mcg, 1.7 mg is 1,700 mcg and 2.4 mg is 2,400 mcg. Compounded prescriptions are written both ways, which is itself a source of confusion — convert to one unit and stay in it for the whole calculation.
What is the approved semaglutide dose escalation schedule?: Table 1 of the Wegovy injection label gives 0.25 mg once weekly for weeks 1 through 4, then 0.5 mg for weeks 5 through 8, 1 mg for weeks 9 through 12, 1.7 mg for weeks 13 through 16, and a maintenance dose of 2.4 mg or 1.7 mg from week 17. Ozempic starts at 0.25 mg for 4 weeks, then 0.5 mg, with increases to 1 mg and a maximum of 2 mg permitted after at least 4 weeks at the preceding dose. Compounded products are not FDA-approved and their schedules are set by the prescriber.
Why do two people on the same semaglutide dose draw different numbers of units?: Because they have different concentrations in the vial. A man with a 10 mg vial in 1 mL of water draws 0.5 mg as 5 units; a man with a 2 mg vial in 2 mL of water draws the identical 0.5 mg as 50 units. Ten times the marks, the same drug. Never copy a unit count from a forum, a friend or a previous vial — recalculate from your own concentration every time the vial changes.
Can I use a normal syringe instead of a U-100 insulin syringe?: Only if you convert correctly. A U-100 insulin syringe is marked in units where 100 units is 1 mL; a standard 1 mL tuberculin syringe is marked in millilitres, so 0.1 mL on that barrel is the same volume as 10 units on the insulin one. Mixing the two scales up is one of the routes to a ten-fold error, so use whichever syringe your prescriber specified and read the scale it is actually printed with.
How many doses are in a semaglutide vial?: Divide the vial strength by the dose: the water volume changes the units you draw but not how much drug is in the vial. A 5 mg vial gives 20 whole doses at 0.25 mg, 10 at 0.5 mg and 2 at 2.4 mg. A 10 mg vial gives 4 whole doses at 2.4 mg. Discard any remainder that is smaller than a full dose rather than rounding up the draw, and follow the beyond-use date your pharmacy printed on the label.

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Next steps

Compare online weight loss providersTelehealth platforms prescribing GLP-1 medication, and what each of them actually dispenses — pen or compounded vial.Every dosing protocolThe same units-and-volume arithmetic for the other injectables, with the conversion printed rather than assumed.

Related calculators

Educational reference, not medical advice. This converts a dose someone has already prescribed; it never suggests one. Compounded semaglutide is not FDA-approved and its concentration varies by pharmacy and by vial, so confirm the mg/mL on your own label before drawing, and check any figure here against your prescriber.