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GLP-1 Dosage Calculator

Convert between milligrams and syringe units for compounded GLP-1 medications. Select your vial concentration and prescribed dose to see exactly how many units to draw.

Compounded GLP-1 medications like semaglutide and tirzepatide are dispensed in multi-dose vials at varying concentrations, typically measured in mg/mL. Patients use U-100 insulin syringes to draw their prescribed dose, which means converting milligrams to syringe units. Getting this conversion right is critical — drawing too little reduces efficacy, and drawing too much increases the risk of side effects. Our calculators do the math for you: enter your vial concentration and prescribed milligram dose, and we show the exact number of units to draw on a standard U-100 insulin syringe.

Calculators by Medication

GLP-1 Receptor Agonist

Semaglutide

Ozempic, Wegovy · 15-20% weight loss

0.25 mg0.5 mg1 mg1.7 mg+1
View calculator
Dual GIP/GLP-1 Receptor Agonist

Tirzepatide

Mounjaro, Zepbound · 20-25% weight loss

2.5 mg5 mg7.5 mg10 mg+2
View calculator

How to Convert mg to Units

1

Find your prescribed dose

Check your dose in milligrams (mg) from your provider.

2

Check the vial concentration

Read your vial label for the concentration in mg/mL.

3

Use the calculator

Select your dose and concentration for the automatic result.

4

Draw into your syringe

Draw up to the unit marking on a U-100 syringe.

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

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Frequently Asked Questions

What is a U-100 insulin syringe and why is it used for GLP-1 injections?
A U-100 insulin syringe is calibrated so that 100 units equals 1 mL of liquid. It is the standard syringe used for subcutaneous injections of compounded GLP-1 medications because it provides precise, small-volume measurements. The unit markings on the syringe do not correspond to milligrams — they measure volume — which is why a dosage calculator is essential for converting your prescribed mg dose into the correct number of syringe units.
How do I convert milligrams to units for a GLP-1 vial?
Divide your prescribed dose in milligrams by the vial concentration in mg/mL, then multiply by 100. For example, if you are prescribed 0.5 mg of semaglutide from a 5 mg/mL vial: 0.5 divided by 5 equals 0.1 mL, multiplied by 100 equals 10 units on a U-100 syringe. The formula is: units = (dose in mg / concentration in mg per mL) x 100.
What concentrations do compounded GLP-1 vials come in?
Compounded semaglutide vials commonly come in concentrations of 1 mg/mL, 2 mg/mL, 2.5 mg/mL, and 5 mg/mL. Compounded tirzepatide vials are typically available at 5 mg/mL, 10 mg/mL, 20 mg/mL, and 30 mg/mL. Always check the label on your specific vial — the concentration determines how many units you need to draw for your prescribed dose.
What is the difference between a compounded GLP-1 vial and a brand-name pen?
Brand-name pens like Ozempic and Mounjaro come pre-filled with a fixed concentration and have built-in dose selectors — you dial your dose and inject without measuring. Compounded vials contain the same active ingredient but require you to draw the correct volume using an insulin syringe. Vials are typically more affordable but demand careful dose calculation. A dosage calculator eliminates the guesswork.
Can I use the same syringe for different GLP-1 medications?
You can use a standard U-100 insulin syringe for any compounded GLP-1 vial, but never mix medications in the same syringe or reuse a syringe between injections. Each injection requires a new, sterile syringe. The unit-to-mg conversion will differ between medications and concentrations, so always verify your calculation before drawing.
How does semaglutide dosing compare to tirzepatide dosing?
Semaglutide maintenance doses typically range from 0.5 mg to 2.4 mg weekly, while tirzepatide doses range from 2.5 mg to 15 mg weekly. Despite the higher milligram numbers, tirzepatide vials come in higher concentrations (up to 30 mg/mL), so the injection volume can be similar. The syringe unit count depends entirely on your vial concentration and prescribed dose — not on the medication alone.
What should I do if I draw the wrong amount from my vial?
If you draw too much, do not inject it. Push the excess back into the vial until the syringe reads the correct unit number, or discard the syringe and start over with a fresh one. If you have already injected an incorrect dose, do not try to compensate — contact your healthcare provider immediately and report the exact amount you administered.
Are compounded GLP-1 medications FDA-approved?
Compounded GLP-1 medications are not FDA-approved products. They are prepared by licensed compounding pharmacies using the same active pharmaceutical ingredients found in brand-name drugs. The FDA permits compounding when brand-name products are in shortage or when a patient has a specific medical need. Your Weight Method provider ensures compounded medications are sourced from pharmacies that meet strict quality and purity standards.

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