GLP-1 Dose Calculator
Convert your prescribed GLP-1 medication dose from mg to units for compounded semaglutide and tirzepatide vials. Enter your vial concentration and prescribed dose to see the exact units to draw on a U-100 insulin syringe. This calculator is for compounded vials only — pre-filled pens (Wegovy®, Ozempic®, Zepbound®, Mounjaro®) have fixed doses and do not require conversion.
Units = (Dose in mg ÷ Concentration in mg/mL) × 100
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“Units” are a syringe measure of volume, not a standardized drug dose. They only translate to mg if you know the exact concentration (mg/mL) of your vial. This applies equally to compounded semaglutide and tirzepatide. Units are not interchangeable across concentrations. If you are not 100% sure of your vial’s concentration or syringe type, confirm with the dispensing pharmacy or your prescribing clinician before injecting.
Semaglutide Dosing Schedule (Wegovy® & Ozempic®)
Semaglutide is available as Wegovy® (for weight management) and Ozempic® (for type 2 diabetes). Both use a gradual dose escalation to minimize GI side effects, sharing the same schedule through 1.0 mg before diverging. The chart below shows each week’s injected dose alongside the estimated total medication in your body, accounting for semaglutide’s ~7-day half-life.
About “Total in Body”: The gray bars are a simplified estimate based on each medication’s published half-life, not an exact pharmacokinetic measurement. They are included to illustrate an important clinical concept: GLP-1 medications accumulate over several weeks of consistent dosing. This is why dose escalation is gradual, and why patients who restart after a gap typically need to re-titrate rather than resume at their previous dose. See how long semaglutide takes to work — and what to expect week by week.
Wegovy® / Ozempic® Weekly Injection Schedule
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|
Weeks 1–4 |
0.25 mg weekly |
|
Weeks 5–8 |
0.5 mg weekly |
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Weeks 9–12 |
1.0 mg weekly |
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Weeks 13–16 |
1.7 mg weekly — Wegovy® |
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Weeks 13+ |
2.0 mg weekly (max)— Ozempic® |
|
Weeks 17+ |
2.4 mg weekly (maintenance) — Wegovy® |
Note: Wegovy® (weight management) and Ozempic® (type 2 diabetes) both contain semaglutide and share the same escalation through 1.0 mg. At week 13, Ozempic® goes directly to its maximum of 2.0 mg, while Wegovy® continues through 1.7 mg to a higher maintenance dose of 2.4 mg.
Wegovy’s 24-week titration reaches a maintenance dose of 2.4 mg. Ozempic shares the same escalation through 1.0 mg but reaches its maximum at 2.0 mg from week 13. Many patients hold a lower dose longer if appetite suppression is already effective or if side effects need more time to resolve. Your provider adjusts based on your response. For a complete breakdown of doses, timing, and what to expect at each stage, see our Semaglutide Weight Loss Dosage Chart.
Tirzepatide Dosing Schedule (Zepbound®/Mounjaro®)
Tirzepatide is a dual GIP/GLP-1 receptor agonist available as Zepbound® (weight management) and Mounjaro® (type 2 diabetes). It follows a 4-week escalation pattern with a shorter half-life (~5 days) than semaglutide.
Zepbound® / Mounjaro® Weekly Injection Schedule
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|
Weeks 1–4 |
2.5 mg weekly |
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Weeks 5–8 |
5.0 mg weekly |
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Weeks 9–12 |
7.5 mg weekly |
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Weeks 13–16 |
10 mg weekly |
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Weeks 17–20 |
12.5 mg weekly |
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Weeks 21+ |
15 mg weekly (maximum) |
Not all patients reach 15 mg. Clinical data shows significant weight loss at 10 mg and 12.5 mg. Dose escalation is guided by tolerability and your provider’s assessment of your response. Many patients find their effective maintenance dose well before the maximum.
How the GLP-1 Dosage Calculator Works
If you’re using a compounded semaglutide or tirzepatide vial (not a pre-filled pen), you need to convert your prescribed dose in milligrams to units on a U-100 insulin syringe. The concentration of your vial determines how many units equal your prescribed dose.
For example, with a 5 mg/mL semaglutide vial and a prescribed dose of 0.5 mg: 0.5 ÷ 5 × 100 = 10 units. With a different concentration (e.g., 2.5 mg/mL), the same 0.5 mg dose would require 20 units. This is why confirming your vial concentration is critical before injecting.
Compounded tirzepatide typically comes in higher concentrations (17 or 20 mg/mL) because the doses are larger. A 5 mg dose from a 20 mg/mL vial equals 25 units, while the same dose from a 17 mg/mL vial equals approximately 29 units.
Not sure which concentration you have?
Your Rivas provider can confirm your vial details, walk you through injection technique, and adjust your semaglutide or tirzepatide dosing at your next visit.
Need help figuring out your concentration? Use this tool
NOTE: This calculator is provided for educational purposes only and is intended to help patients understand unit conversions on a U-100 insulin syringe. It does not constitute medical advice and does not replace the guidance of your prescribing provider. Medication doses at Rivas Medical Weight Loss are determined by a licensed physician and should not be adjusted without provider approval.
Frequently Asked Questions about GLP-1 Dose Calculators
It depends on your vial concentration. With a 5 mg/mL vial, 0.25 mg = 5 units. With a 2.5 mg/mL vial, 0.25 mg = 10 units. Always check the label on your specific vial. For full dose progression guidance, see our Semaglutide Weight Loss Dosage Chart.
With a 5 mg/mL vial, 1.0 mg = 20 units. With a 2.5 mg/mL vial, 1.0 mg = 40 units. The concentration determines the conversion.
With a 20 mg/mL vial, 5 mg = 25 units. With a 17 mg/mL vial, 5 mg ≈ 29 units. Use the calculator above for exact conversions.
A standard U-100 insulin syringe (1.0 mL / 100 units) is used for compounded GLP-1 vials. This calculator is designed specifically for U-100 syringes. Do not use other syringe types without consulting your provider.
No. Brand-name pre-filled pens (Wegovy, Ozempic, Zepbound, Mounjaro) deliver fixed doses and do not require mg-to-unit conversion. This calculator is only for compounded vials dispensed by a pharmacy.
Semaglutide is a GLP-1 receptor agonist. Tirzepatide is a dual GIP/GLP-1 receptor agonist, meaning it activates two hormonal pathways involved in appetite regulation and blood sugar control. Both are injected once weekly. Clinical trials have shown tirzepatide produces greater average weight loss, though individual results vary. Your provider can help determine which medication is right for you.
Compounded semaglutide is commonly available in 2.5 mg/mL and 5 mg/mL concentrations. Compounded tirzepatide typically comes in 17 mg/mL and 20 mg/mL. However, concentrations can vary by pharmacy. Always verify the concentration printed on your vial label.
Drawing too many or too few units means you will receive the wrong dose of medication. This can lead to increased side effects (if too much) or reduced effectiveness (if too little). If you are unsure about your dose, contact your prescribing provider or dispensing pharmacy before injecting.
Medically reviewed by Eli Luft, PA-C · Updated March 2026
Rivas Medical Weight Loss — 34 years of physician-led weight management across Maryland, Virginia, and Florida. This calculator supports compounded semaglutide and tirzepatide vials for any concentration levels.