Mounjaro & Zepbound injection date calculator
Mounjaro & Zepbound are tirzepatide, dosed once weekly — your next injection is due exactly 7 days after the last one. Enter your last shot date and the calculator returns the due date, the latest the label allows a missed dose (4 days), and the earliest you could switch your injection day (72 hours between doses).
Calculator
Dates come from your medication's labelled schedule; they are planning arithmetic, not a prescription. If you are unsure about a late or missed dose, the person to ask is your prescriber.
The label rules
- Schedule: once weekly, any time of day, with or without food.
- Missed dose: take it within 4 days (96 hours); later than that, skip to the next scheduled dose. Details →
- Changing day: allowed when at least 72 hours separate two doses.
Between doses
Tirzepatide has a half-life of about 5 days (120 hours), so it never fully clears between weekly shots — each dose stacks on what remains. The sourced tirzepatide half-life page →
Reminders instead of arithmetic
Bo schedules your weekly shot, warns you before it is due, and draws your estimated level curve from your own logged doses.
Educational information only. Bo is a tracking app, not a medical device, and nothing here is medical advice, a dosing recommendation, or a substitute for your prescriber. Half-lives are population averages from the sources cited on each row; individual clearance varies with body weight, kidney and liver function, and other medication.