Dosage calculator

SEMAGLUTIDE Dosage Calculator: Reconstitution and Units

Quick answer

To calculate semaglutide dosage, divide your target dose (mg) by the vial concentration. Concentration = vial mg ÷ BAC water mL. For a 5 mg vial with 2 mL BAC water: concentration is 2.5 mg/mL. A 0.5 mg dose equals 0.2 mL (20 U-100 units) on a standard insulin syringe.

Updated October 17, 2026
2 sources
Educational use · not medical advice

Semaglutide Calculator Tool

Enter your vial strength, BAC water volume, and target dose below. The calculator outputs concentration (mg/mL), draw volume (mL), and U-100 units. Educational and research use only.

Vial

Weekly dose

Fills the calculator below. Choose your BAC water in the calculator.

On this page

How much bac water for each semaglutide vial size

BAC water doesn't change how much semaglutide is in the vial, only how concentrated the mix is. Less water makes each unit stronger; more water spreads the same amount over more units. Each answer uses a 0.25 mg dose, the starting dose in the Wegovy and Ozempic labels, so the mixes are easy to compare.

How much bac water for 2 mg semaglutide?

It's your choice: the water sets the strength of the mix, not the amount of semaglutide. With 1 mL, a 2 mg vial is 2 mg/mL and a 0.25 mg dose is 12.5 units on a U-100 syringe; 2 mL gives 1 mg/mL (25 units); 3 mL gives 0.67 mg/mL (37.5 units).

Every dose for a 2 mg vial

How much bac water for 3 mg semaglutide?

It's your choice: the water sets the strength of the mix, not the amount of semaglutide. With 1 mL, a 3 mg vial is 3 mg/mL and a 0.25 mg dose is 8.3 units on a U-100 syringe; 2 mL gives 1.5 mg/mL (16.7 units); 3 mL gives 1 mg/mL (25 units).

Every dose for a 3 mg vial

How much bac water for 5 mg semaglutide?

It's your choice: the water sets the strength of the mix, not the amount of semaglutide. With 1 mL, a 5 mg vial is 5 mg/mL and a 0.25 mg dose is 5 units on a U-100 syringe; 2 mL gives 2.5 mg/mL (10 units); 3 mL gives 1.67 mg/mL (15 units).

Every dose for a 5 mg vial

How much bac water for 10 mg semaglutide?

It's your choice: the water sets the strength of the mix, not the amount of semaglutide. With 1 mL, a 10 mg vial is 10 mg/mL and a 0.25 mg dose is 2.5 units on a U-100 syringe; 2 mL gives 5 mg/mL (5 units); 3 mL gives 3.33 mg/mL (7.5 units).

Every dose for a 10 mg vial

Semaglutide Reconstitution by Vial Size

Doses are the steps in the FDA labels: Wegovy goes 0.25 mg, 0.5 mg, 1 mg and 1.7 mg once weekly, 4 weeks each, then 2.4 mg (or 1.7 mg) to maintain; Ozempic starts at 0.25 mg for 4 weeks, then 0.5 mg, and can go to 1 mg and then 2 mg, its maximum (see sources). Those products come in ready-to-use pens; these tables are for powder vials mixed with BAC water. They show the math for each mix, not which dose to take.

Each cell is the U-100 syringe reading for that dose, with the mL to draw under it.
Over 1 mL more than a 1 mL (100-unit) syringe holds: the calculator splits it into more than one injection.
Over vial the dose is more than the vial contains.

2 mg semaglutide vial

1 mL BAC water = 2 mg/mL · 2 mL BAC water = 1 mg/mL · 3 mL BAC water = 0.67 mg/mL

2 mg semaglutide vial: U-100 units per dose with 1, 2 or 3 mL BAC water
Weekly dose	1 mL	2 mL	3 mL
0.25 mg	12.5 units0.13 mL	25 units0.25 mL	37.5 units0.38 mL
0.5 mg	25 units0.25 mL	50 units0.5 mL	75 units0.75 mL
1 mg	50 units0.5 mL	100 units1 mL	150 units1.5 mLOver 1 mL
1.7 mg	85 units0.85 mL	170 units1.7 mLOver 1 mL	255 units2.55 mLOver 1 mL
2.4 mg	Over vial	Over vial	Over vial

3 mg semaglutide vial

1 mL BAC water = 3 mg/mL · 2 mL BAC water = 1.5 mg/mL · 3 mL BAC water = 1 mg/mL

3 mg semaglutide vial: U-100 units per dose with 1, 2 or 3 mL BAC water
Weekly dose	1 mL	2 mL	3 mL
0.25 mg	8.3 units0.0833 mL	16.7 units0.17 mL	25 units0.25 mL
0.5 mg	16.7 units0.17 mL	33.3 units0.33 mL	50 units0.5 mL
1 mg	33.3 units0.33 mL	66.7 units0.67 mL	100 units1 mL
1.7 mg	56.7 units0.57 mL	113.3 units1.13 mLOver 1 mL	170 units1.7 mLOver 1 mL
2.4 mg	80 units0.8 mL	160 units1.6 mLOver 1 mL	240 units2.4 mLOver 1 mL

5 mg semaglutide vial

1 mL BAC water = 5 mg/mL · 2 mL BAC water = 2.5 mg/mL · 3 mL BAC water = 1.67 mg/mL

5 mg semaglutide vial: U-100 units per dose with 1, 2 or 3 mL BAC water
Weekly dose	1 mL	2 mL	3 mL
0.25 mg	5 units0.05 mL	10 units0.1 mL	15 units0.15 mL
0.5 mg	10 units0.1 mL	20 units0.2 mL	30 units0.3 mL
1 mg	20 units0.2 mL	40 units0.4 mL	60 units0.6 mL
1.7 mg	34 units0.34 mL	68 units0.68 mL	102 units1.02 mLOver 1 mL
2.4 mg	48 units0.48 mL	96 units0.96 mL	144 units1.44 mLOver 1 mL

10 mg semaglutide vial

1 mL BAC water = 10 mg/mL · 2 mL BAC water = 5 mg/mL · 3 mL BAC water = 3.33 mg/mL

10 mg semaglutide vial: U-100 units per dose with 1, 2 or 3 mL BAC water
Weekly dose	1 mL	2 mL	3 mL
0.25 mg	2.5 units0.025 mL	5 units0.05 mL	7.5 units0.075 mL
0.5 mg	5 units0.05 mL	10 units0.1 mL	15 units0.15 mL
1 mg	10 units0.1 mL	20 units0.2 mL	30 units0.3 mL
1.7 mg	17 units0.17 mL	34 units0.34 mL	51 units0.51 mL
2.4 mg	24 units0.24 mL	48 units0.48 mL	72 units0.72 mL

How to Calculate Semaglutide Dosage

Three steps convert any vial and BAC water combination into the exact volume to draw on a U-100 insulin syringe.

Step 1 — Calculate concentration (mg/mL)
Divide the total peptide in the vial (mg) by the volume of BAC water you added (mL). For example: a 5 mg Semaglutide vial reconstituted with 2 mL BAC water gives 5 ÷ 2 = 2.5 mg/mL.
Step 2 — Calculate draw volume (mL)
Divide your target dose (mg) by the concentration (mg/mL). For a 0.5 mg dose at 2.5 mg/mL: 0.5 ÷ 2.5 = 0.2 mL. This is the exact volume to draw into the syringe.
Step 3 — Convert to U-100 syringe units
Multiply the draw volume (mL) by 100. For 0.2 mL: 0.2 × 100 = 20 U-100 units. Read this number on the unit markings of a standard insulin syringe.

Dosage Formula

Concentration formula

Concentration (mg/mL) = Vial mg ÷ BAC water mL

Draw volume formula

Draw volume (mL) = Dose (mg) ÷ Concentration (mg/mL)

U-100 syringe units

U-100 units = Draw volume (mL) × 100

These three formulas apply to any Semaglutide vial, regardless of size. U-100 is the standard insulin-syringe scale: 100 units = 1 mL.

Example Semaglutide Calculations

Step-by-step worked examples using common vial sizes. Results are for illustrating the math only.

Example

5 mg vial + 2 mL BAC water, 0.5 mg dose

Given

Vial: 5 mg
BAC water: 2 mL
Target dose: 0.5 mg

Result

20 units

0.2 mL at 2.5 mg/mL

Concentration: 5 ÷ 2 = 2.5 mg/mL
Draw volume: 0.5 ÷ 2.5 = 0.2 mL
U-100 units: 0.2 × 100 = 20 units

Example

5 mg vial + 2 mL BAC water, 1 mg dose

Given

Vial: 5 mg
BAC water: 2 mL
Target dose: 1 mg

Result

40 units

0.4 mL at 2.5 mg/mL

Concentration: 5 ÷ 2 = 2.5 mg/mL
Draw volume: 1 ÷ 2.5 = 0.4 mL
U-100 units: 0.4 × 100 = 40 units

Example Semaglutide Dosage Table

Common vial and BAC water combinations with calculated concentration, draw volume, and U-100 syringe units. For education only — verify your vial label before use.

Vial (mg)	BAC water (mL)	Concentration	Dose (mg)	Draw (mL)	U-100 units
5 mg	2 mL	2.5 mg/mL	0.25 mg	0.1 mL	10 units
5 mg	2 mL	2.5 mg/mL	0.5 mg	0.2 mL	20 units
5 mg	2 mL	2.5 mg/mL	1 mg	0.4 mL	40 units
5 mg	5 mL	1 mg/mL	0.5 mg	0.5 mL	50 units

Semaglutide Reconstitution Guide

Research semaglutide vials are supplied as lyophilised powder. Approved pen injectors (Ozempic, Wegovy) come pre-filled and do not require reconstitution. For research vials:

Swab both stoppers with alcohol.
Inject BAC water slowly along the vial wall.
Swirl gently — do not shake. Solution should be clear.
Store refrigerated. Avoid repeated freeze-thaw cycles.

Important

For educational and research purposes only. Not medical advice. Consult a licensed healthcare professional before making any medical or health-related decisions.

Frequently Asked Questions

How do I calculate semaglutide draw volume?

Divide your dose (mg) by the concentration. For 5 mg + 2 mL BAC: 2.5 mg/mL. For 0.5 mg: 0.5 ÷ 2.5 = 0.2 mL = 20 U-100 units.

What are U-100 syringe units?

U-100 is the standard scale for insulin syringes. 100 units = 1.0 mL. That means 10 units = 0.1 mL, 50 units = 0.5 mL. Multiply any draw volume in mL by 100 to get the U-100 units reading.

Do I need to recalculate if I change the amount of BAC water?

Yes. Changing BAC water volume changes the concentration (mg/mL), which changes the draw volume for the same mg dose. Always recalculate using: concentration = vial mg ÷ BAC water mL, then draw volume = dose mg ÷ concentration.

Does the calculator apply to Ozempic or Wegovy pens?

No. Pre-filled pens deliver a fixed dose and do not require reconstitution math. This calculator is for lyophilised research vials that require mixing with BAC water.

Sources & references

Dose steps come from the FDA prescribing information for Wegovy and Ozempic. The vial tables are reconstitution math only: they turn a vial size, a BAC water volume and a dose into mL and U-100 units. They don't recommend a dose.

Wegovy (semaglutide) injection and tablets: US Prescribing Information (FDA, revised 01/2026)Section 2.2, Table 1 (injection): 0.25 mg, 0.5 mg, 1 mg and 1.7 mg once weekly for 4 weeks each, then a maintenance dose of 2.4 mg (recommended) or 1.7 mg once weekly.
Ozempic (semaglutide) injection: US Prescribing Information (FDA, revised 10/2025)Section 2.2: 0.25 mg once weekly for 4 weeks, then 0.5 mg; may increase to 1 mg and then 2 mg after at least 4 weeks on each; maximum 2 mg once weekly.

Updated October 17, 2026