Last updated: May 2026

Semaglutide Dosage Calculator — Units to mL

Quick answer: A 0.25 mg starting dose from a 5 mg/mL vial is 0.05 mL = 5 units on a U-100 syringe. Formula: Volume (mL) = Dose (mg) ÷ Concentration (mg/mL).

About this calculator

The semaglutide draw volume calculator converts a prescribed dose into the volume to draw from a compounded vial using Volume (mL) = Dose (mg) ÷ Concentration (mg/mL). Designed for people using compounded semaglutide vials with an insulin syringe — not pre-filled branded pens. Supports 2.5, 5, and 10 mg/mL concentrations plus custom entries. To check your BMI before or during GLP-1 treatment, use the BMI calculator. Free, instant, no login.

How to use this calculator

You need two pieces of information: your vial concentration (printed on the pharmacy label in mg/mL) and your prescribed dose in mg.

Select your vial concentration using the preset buttons or enter a custom value. Use the dose slider to set your dose. The draw volume and U-100 syringe units update instantly.

The calculator assumes a U-100 insulin syringe (1 unit = 0.01 mL). Always verify the drawn volume against your syringe markings before injecting.

Worked example

Example — 0.5 mg dose from a 5 mg/mL vial

Vial concentration: 5 mg/mL

Prescribed dose: 0.5 mg

Draw = 0.5 ÷ 5 = 0.10 mL = 10 units (U-100 syringe)

Example — 1.0 mg dose from a 2.5 mg/mL vial

Vial concentration: 2.5 mg/mL

Prescribed dose: 1.0 mg

Draw = 1.0 ÷ 2.5 = 0.40 mL = 40 units (U-100 syringe)

Common dose reference table

Dose2.5 mg/mL vial5 mg/mL vial10 mg/mL vial
0.25 mg0.10 mL (10 U)0.05 mL (5 U)0.025 mL (3 U)
0.5 mg0.20 mL (20 U)0.10 mL (10 U)0.05 mL (5 U)
1.0 mg0.40 mL (40 U)0.20 mL (20 U)0.10 mL (10 U)
1.7 mg0.68 mL (68 U)0.34 mL (34 U)0.17 mL (17 U)
2.4 mg0.96 mL (96 U)0.48 mL (48 U)0.24 mL (24 U)

Typical semaglutide titration schedule

Standard compounded vial protocol. Your prescriber sets your actual schedule — titration timing and doses vary. Full titration guide →

0 0.5 1.0 1.5 2.0 mg/wk 0.25 mg Wks 1–4 0.5 mg Wks 5–8 1.0 mg Wks 9–12 1.7 mg Wks 13–16 2.4 mg Wk 17+ Typical schedule — your prescriber sets actual timing and doses

Frequently asked questions

How do I calculate semaglutide dosage from a compounded vial?
Divide your prescribed dose in mg by your vial concentration in mg/mL. For example, a 0.5 mg dose from a 5 mg/mL vial equals 0.5 ÷ 5 = 0.10 mL, which is 10 units on a U-100 insulin syringe. The calculator does this division automatically. Always confirm the concentration printed on your specific pharmacy vial, as compounded semaglutide concentrations vary between pharmacies.
What concentrations does compounded semaglutide come in?
Compounded semaglutide commonly comes in concentrations of 2.5 mg/mL, 5 mg/mL, and 10 mg/mL, though the exact concentration depends on your compounding pharmacy. The concentration is always printed on the vial label. This calculator supports all three common concentrations plus a custom input field for any pharmacy-specific concentration. Always use the concentration stated on your own vial — do not assume a standard concentration.
How many units should I draw on an insulin syringe?
On a standard U-100 insulin syringe, each unit mark equals 0.01 mL. To find the number of units, multiply your draw volume in mL by 100. For example, 0.10 mL = 10 units; 0.20 mL = 20 units. The calculator computes this automatically. Note that some syringes are U-40 (each unit = 0.025 mL) — using the wrong syringe type will give you the wrong dose. This calculator assumes U-100 throughout.
Is this calculator suitable for Ozempic or Wegovy pens?
No. This calculator is designed for compounded semaglutide supplied in multi-dose vials that you draw from yourself using an insulin syringe. Brand-name pens (Ozempic, Wegovy) are pre-dosed and do not require draw volume calculations — the dose is dialled directly on the pen device. This calculator applies only to vial-and-syringe preparations from compounding pharmacies. See: compounded vial vs brand pen — full explainer.
What is the difference between my semaglutide dose and my draw volume?
Your dose is the amount of semaglutide you inject, measured in milligrams (mg) — for example, 0.5 mg. Your draw volume is the amount of liquid you pull into the syringe, measured in milliliters (mL). The two differ because the vial concentration determines how many mL contain that dose. A 0.5 mg dose from a 5 mg/mL vial requires drawing 0.10 mL; the same dose from a 2.5 mg/mL vial requires 0.20 mL. Always enter the concentration printed on your specific vial label to get the correct draw volume.

Dosing guide

Learn about dose escalation, injection preparation, and storage in the full reference guide. Semaglutide Dosing Guide →

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Related guides

How many units is 0.25 mg semaglutide? → What are GLP-1 medications? → Why GLP-1 doses increase over time → How to store GLP-1 medications → What to do if you miss a GLP-1 dose → Injectable vs oral semaglutide → What BMI do you need for semaglutide? → Wegovy vs Zepbound dosing →

How this is calculated

This calculator divides your prescribed dose by the vial concentration to find the injection volume, then converts that volume to insulin-syringe units (volume in mL × 100 for a U-100 syringe). It is arithmetic only — nothing you enter is stored or sent anywhere, and the result is not medical advice. Always confirm your dose with your prescriber.

References

  1. WEGOVY (semaglutide) Prescribing Information — dosing & titration — FDA / DailyMed, 2021
  2. OZEMPIC (semaglutide) Prescribing Information — dosing & titration — FDA / DailyMed, 2017
  3. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1) — N Engl J Med, 2021
  4. FDA Alert: Dosing Errors With Compounded Injectable Semaglutide Products — U.S. FDA, 2024
  5. Administration Errors of Compounded Semaglutide Reported to a Poison Control Center — Case Series — J Am Pharm Assoc, 2023
  6. Challenges With GLP-1 Agonist Initiation: A Case Series of Semaglutide Overdose Administration Errors — Clin Toxicol (Phila), 2024
  7. FDA Warns Consumers Not to Use Counterfeit Ozempic (semaglutide) Found in the U.S. Supply Chain — U.S. FDA, 2023
  8. FDA Concerns With Unapproved GLP-1 Drugs Used for Weight Loss — U.S. FDA

Citations are provided for transparency and education. They do not imply the cited authors or bodies endorse this tool. Always confirm dosing with your prescriber.

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InjectBuddy/Semaglutide Dosage Calculator — Units to mL

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