GLP-1 Split Dose Calculator

Why split dosing?

The FDA-approved regimen for both semaglutide (Wegovy/Ozempic) and tirzepatide (Zepbound/Mounjaro) is a single subcutaneous injection once per week [2, 4]. However, some patients — especially during the early titration weeks — experience significant nausea, vomiting, or GI distress that limits their ability to tolerate the full dose at once.

Prescribers in the compounded GLP-1 market sometimes recommend splitting the weekly dose into 2 or 3 smaller injections, spaced evenly across the week. The total weekly milligrams remain the same; only the per-injection amount changes.

This is off-label use. There are no published clinical trials specifically studying split-dose GLP-1 regimens for weight management. The pharmacokinetics of semaglutide (half-life ~7 days) and tirzepatide (half-life ~5 days) support once-weekly dosing, and splitting may alter the plasma concentration profile. Always discuss split dosing with your prescriber before changing your injection schedule.

The math

The calculation is straightforward division. For a weekly dose of W mg split into N injections:

per-injection mg = W ÷ N

Then convert to syringe units using the U-100 standard [1]:

per-injection units = (per-injection mg × 100) ÷ concentration (mg/mL)

For example, splitting a 2.4 mg/week semaglutide dose into 2 injections at a 5 mg/mL concentration:

1.2 mg per injection × 100 ÷ 5 = 24 units per injection

Scheduling

The goal is to space injections as evenly as possible across the week:

• 2 injections/week: Monday + Thursday (every 3-4 days) or any two days ~3.5 days apart.
• 3 injections/week: Monday + Wednesday + Friday (every 2-3 days).

Consistency matters more than the exact days. Pick days you can commit to and stick with them each week.

Important safety disclaimer

Split dosing is off-label for all GLP-1 receptor agonists approved for weight management. This calculator performs arithmetic only and does not provide medical advice. Do not change your injection schedule without discussing it with your prescriber. Weight Loss Rankings does not provide medical advice, diagnosis, or treatment recommendations.

Related tools and research

• GLP-1 unit ↔ mg converter — convert between milligrams and syringe units at any concentration.
• GLP-1 reverse dose calculator — verify the mg dose from your syringe units.
• GLP-1 vial transition calculator — recalculate syringe units when your vial concentration changes.
• GLP-1 dose plotter — visualize plasma concentration over time at each titration step.
• GLP-1 washout calculator — estimate how long the drug stays in your system after stopping.
• PCAB accreditation investigation — how to evaluate the pharmacy filling your prescription.