Tool · Pen duration
How long does your pen actually last?
Pen size, per-injection dose, frequency, start date, optional pen cost. Get doses per pen, weeks of supply, refill-by date, and cost per month. Presets cover every Mounjaro, Wegovy, Ozempic, and Zepbound dose strength.
Common maintenance dose. 4 weekly 5mg doses per pen.
Pen duration
Doses per pen
4
Total doses (in hand)
4
Weeks of supply
4.0
(28 days)
Refill by
26 May 2026
Order ~2 weeks earlier to avoid gaps
How the math works
The numbers behind the result
- Doses per pen = floor(total mg ÷ per-injection mg). Floor because partial doses are typically discarded for stability and sterility on multi-dose pens.
- Days per dose: 7 (weekly), 10, or 14 (microdose / taper). Frequency drives both supply duration and per-month cost.
- Weeks of supply = total doses × days per dose ÷ 7.
- Refill by date = start date + total days. Order ~2 weeks earlier to avoid supply gaps.
- Cost per month = (pen cost ÷ doses per pen) × (4.345 weeks per month × 7 ÷ days per dose). Uses 4.345 for the average month.
Pen presets reflect Eli Lilly KwikPen / Zepbound autoinjector inserts and Novo Nordisk FlexTouch / Wegovy specs. Numbers held to the labeled per-pen drug content. Override the inputs if your pen differs (e.g. compounded sources, alternate concentration).
Where to read more
Pricing and supply by region
The calculator handles pen-level math. For region-specific pricing, supply state, and vendor scorecards, see Panya's compound pages.