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GLP-1 Dosage Calculator

Educational tool to translate a target weekly GLP-1 dose (mg/week) and vial concentration (mg/mL) into per-injection mg, mL, and U-100 syringe units for the schedule you choose.

Enter your weekly dose and vial concentration to start.

Try:

Enter 0.01 - 200 mg/week.

Adds another weekly-dose phase (not a single injection).

Enter 0.01 - 1000 mg/mL (typical range 1 - 30).

Add this to see doses per vial and days of supply.

Adds a separate vial row for another concentration or size.

How it works

Three short steps. The math is purely arithmetic - no pharmacokinetics, no half-life modelling, just unit conversion you can sanity-check before you draw.

  1. Enter your weekly target dose

    Type your weekly target in milligrams - for example, 0.25 mg/week of semaglutide for a starting dose, or 2.5 mg/week as a typical maintenance dose.

  2. Enter the vial concentration

    Read the concentration off the vial label in mg/mL (commonly 5 mg/mL or 10 mg/mL for compounded GLP-1s) and type it in.

  3. Pick how often you inject

    Choose your dosing interval - weekly, twice weekly, every other day, daily, or a custom interval. The calculator splits the weekly target across those injections.

  4. Read mg, mL, and U-100 syringe units per dose

    You get milligrams per injection, the volume in mL to draw, the matching marking on a U-100 insulin syringe, and how long the vial will last at that schedule.

Worked example

2.5 mg/week semaglutide at 10 mg/mL, dosed once a week

You enter
Weekly dose
2.5 mg
Concentration
10 mg/mL
Frequency
Once weekly
Vial size
2 mL
You get
mg per injection
2.5 mg
Volume per injection
0.25 mL
U-100 syringe units
25 units
Doses per vial
8 doses
Days of supply
56 days

Once a week you draw 0.25 mL (the 25-unit mark on a U-100 insulin syringe). A 2 mL vial covers about 8 weeks at this schedule before you need a refill.

Assumptions and limitations

Every formula on this calculator is currently labelled as a placeholder. The full list - what is modelled, what is not, and the underlying arithmetic - lives on its own page.

Read the full assumptions and limitations

Frequently asked questions

What does the GLP-1 dosage calculator do?
It converts a target weekly GLP-1 dose (in mg/week) and a vial concentration (in mg/mL) into the milligrams and millilitres you would draw per injection across common dosing intervals - daily, every other day, twice weekly, weekly, or a custom schedule. It also estimates the marking on a U-100 insulin syringe, full doses per vial, and days of supply.
How do I read U-100 syringe units for semaglutide or tirzepatide?
U-100 insulin syringes are marked in units where 100 units equal 1 mL (so 1 unit equals 0.01 mL). The calculator multiplies your draw volume in mL by 100 to give you the unit marking - for example, a 0.07 mL draw is 7 units. Always confirm against the markings on your specific syringe before drawing.
What concentrations are common for compounded semaglutide and tirzepatide vials?
Compounded GLP-1 vials typically ship at 5 mg/mL or 10 mg/mL for semaglutide, and 5 mg/mL or 10 mg/mL for tirzepatide. Branded products ship in pre-filled pens with fixed per-click dosing and are not the use case for this tool. Always confirm the concentration printed on the vial label before calculating.
How do I split a weekly GLP-1 dose into multiple injections?
Pick a frequency in the calculator (e.g. twice weekly or every other day) and the math will divide your weekly target across the resulting doses. Splitting evenly across the week can smooth side effects for some people, but the steady-state weekly exposure is the same as a single injection. Always check with your prescriber before changing your interval.
Why does the doses-per-vial number round down?
A partial last dose is not a useful planning unit for most users, so the calculator floors the result and reports the leftover volume as a remainder. "Days of supply" only counts whole doses, so it will never overstate how long a vial lasts.
Does this calculator account for the difference between semaglutide, tirzepatide, and other GLP-1s?
No. The math is purely arithmetic: weekly mg divided by doses per week, then divided by concentration. It does not model receptor binding, half-life, or potency differences between GLP-1 agonists. Use it for unit conversion, not protocol selection - see the disclaimer for more.
What does "weekly mL total" mean?
It's the total millilitres you would draw over a full week at steady state, calculated as weekly_mg divided by concentration_mg_per_mL. It's useful for forecasting how many vials you need across a multi-month plan and for sanity-checking your per-injection volume against your weekly target.
Is this tool medical advice?
No. Every formula is labelled as a placeholder and the site exists for educational unit-conversion only. Always confirm any number with a licensed clinician and the actual product labelling for your medication. See the disclaimer for the full statement.