DoseMarks
FDA-approved (brand)GLP-1 receptor agonist

Semaglutide Dosage Calculator

Semaglutide is a once-weekly GLP-1 medication. Doses are small — often a fraction of a milligram — so the amount of water you add makes a big difference to how many units you draw.

Common vials
2 mg · 5 mg · 10 mg
Dosing frequency
Once weekly
Half-life
About 1 week

FDA-approved as Ozempic® and Wegovy®. Compounded vials are not FDA-approved.

Step 1

Your vial & dose

U-100 syringes
mg
mL

Step 2

mg

Step 3

Syringe size

Smaller barrels have finer marks, which makes small doses easier to read.

Live syringe preview · 100-unit

010203040506070809010010u

Draw to

10 units

= 0.1 mL of liquid

Concentration
2.5 mg/mL
Each unit contains
25 mcg
Your dose
250 mcg
Doses per vial
20
Show the math
  1. Concentration = 5 mg ÷ 2 mL = 2.5 mg/mL
  2. Volume = 0.25 mg ÷ 2.5 mg/mL = 0.1 mL
  3. Units = 0.1 mL × 100 = 10 units

Dosing schedule

Label titration schedule (Wegovy®)

Based on the FDA label for Wegovy®: 0.25 mg weekly for 4 weeks, then step up every 4 weeks to a 2.4 mg maintenance dose. Your prescriber may hold or adjust any step.

  1. Weeks 1–4

    250 mcg

  2. Weeks 5–8

    500 mcg

  3. Weeks 9–12

    1 mg

  4. Weeks 13–16

    1.7 mg

  5. Weeks 17+

    2.4 mg

Calculated for your mix: 2.5 mg/mL, 100-unit syringe
WeeksWeekly doseVolumeDraw toNote
1–4250 mcg0.1 mL10 unitsStarting dose← your dose
5–8500 mcg0.2 mL20 units
9–121 mg0.4 mL40 units
13–161.7 mg0.68 mL68 units
17+2.4 mg0.96 mL96 unitsMaintenance

How to mix

How to reconstitute a peptide vial in 5 steps

  1. 01

    Clean

    Wash your hands. Wipe the rubber tops of the peptide vial and the bacteriostatic water with an alcohol swab and let them air-dry.

  2. 02

    Draw the water

    With a new syringe, draw 2 mL of bacteriostatic water — the same number you entered in the calculator. Use several draws if it’s more than your syringe holds.

  3. 03

    Add it slowly

    Insert the needle at an angle and let the water run down the inside wall of the vial, not straight onto the powder.

  4. 04

    Swirl, don’t shake

    Gently swirl or roll the vial until the powder dissolves completely. The liquid should look clear.

  5. 05

    Label & refrigerate

    Write the date and concentration (2.5 mg/mL) on the vial and keep it in the fridge.

Storing a mixed vial

  • Keep it refrigerated at 2–8 °C (36–46 °F). Don’t freeze it.
  • Protect it from light and heat.
  • Follow the beyond-use date on your pharmacy label. If the liquid turns cloudy or has particles, don’t use it.

Please read before injecting

Always confirm your dose, concentration and syringe markings with your prescriber or pharmacist. Small calculation errors can have serious consequences. This tool does math — it doesn’t tell you what dose to take.

Sources

References

Last updated October 2026. Example vial: 5 mg + 2 mL = 2.5 mg/mL.

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