Peptide Cycle Tracker: Counting On Days, Off Days, Steps
A peptide cycle tracker keeps a calendar of on days, off days and dose changes, so the log shows what is due today and where a schedule stands. PepTrac for iPhone stores a cycle as on days and off days per protocol, and off days pause the dose-step clock. It records the schedule you enter and never suggests how long to cycle.
What is a peptide cycle?
A peptide cycle is a repeating pattern of dosing days and rest days, sometimes with a planned end date. It is a scheduling word, not a clinical standard, and no cycle length is correct for every compound. This page explains the bookkeeping only and does not suggest what cycle to run. Some medicines are not cycled at all. The Ozempic label tells patients to administer semaglutide once weekly on the same day each week,[1] and the Mounjaro label describes once-weekly tirzepatide dosing.[2] A tracker therefore has to handle three cases: continuous dosing with no off days, a repeating pattern such as five days on and two days off, and a defined block with a break afterward. PepTrac covers all three by storing on days and off days for each protocol. If both are blank, every day counts as an on day. Your prescriber decides which pattern applies to you.
How does a tracker count cycle days?
A cycle tracker keeps two counts that diverge as soon as a rest day appears: calendar days and on-cycle days. Calendar days are simply the days since the protocol started. On-cycle days count only the days that fall inside the on portion of the repeating window. Take a protocol with five days on and two days off, which repeats every seven days. After 14 calendar days, two full windows have passed, so the on-cycle count is 10, not 14. After 7 calendar days it is 5. PepTrac calculates this from the protocol's start date, its on days, and its off days, and it counts the days from the start up to the current day. The count matters because other features, such as the dose-step schedule, run on on-cycle days. With no off days entered, the two counts are identical.
| Calendar days elapsed | On-cycle days counted | Off days passed |
|---|---|---|
| 7 | 5 | 2 |
| 14 | 10 | 4 |
| 21 | 15 | 6 |
| 28 | 20 | 8 |
What is the difference between a cycle and a titration schedule?
A cycle answers when, and a titration schedule answers how much. A cycle is the pattern of on and off days. A titration schedule is an ordered list of steps, and each step has a dose and a duration. The Ozempic label shows the idea: it says to start at 0.25 mg once weekly for 4 weeks and then increase to 0.5 mg once weekly.[1] The Mounjaro label describes increasing in 2.5 mg increments after at least 4 weeks on the current dose.[2] These are label facts, not advice, and your prescriber sets your own plan. PepTrac keeps the two ideas separate. You enter the steps your prescriber gave you, with a dose and a number of days for each, and you separately enter any on and off days. The app then shows the dose for the step you are currently on. It never picks a step or a dose for you.
What happens to a dose-step schedule during off days?
In PepTrac, off days pause the step clock. Step progress is measured in on-cycle days, so a rest day does not move you toward the next step, and it does not rewind progress either. The last step is a plateau: once you reach it, the dose holds there until you change the schedule. Here is an arithmetic example with three steps: 0.25 mg for 28 days, 0.5 mg for 28 days, then 1 mg with no end. With no off days, day 30 falls in the second step, so it resolves to 0.5 mg. With 5 days on and 2 days off, a 28-day step needs 28 on-cycle days, and that takes 39 calendar days. These amounts only illustrate the counting and are not a suggested titration. If no steps are entered, the app falls back to the flat dose saved for the compound.
| Step | Dose | Duration | Active when on-cycle days elapsed are |
|---|---|---|---|
| 1 | 0.25 mg | 28 days | 0 to 27 |
| 2 | 0.5 mg | 28 days | 28 to 55 |
| 3 (holds) | 1 mg | No end | 56 or more |
How do missed doses and breaks show up in a log?
A missed dose stays visible in your history as a scheduled entry with no log against it. PepTrac does not fill the gap for you. The level curve counts only doses you actually logged, so a skipped dose or a longer break shows up as a curve that falls instead of holding steady. The curve is an estimate with a shaded sensitivity range, not a lab result, and it is relative to the compound's own scale. What to do about a late dose depends on the medicine. The Ozempic label says to administer a missed dose as soon as possible within 5 days,[1] while the Mounjaro label gives a window of 4 days, or 96 hours.[2] Those windows are specific to those labels, so ask your pharmacist about your product. A tracker's job is to show how many days have passed since the last logged dose.
What should you record at the end of a cycle?
Record facts, not conclusions. Useful entries are the start and end dates, the total number of doses logged, the injection sites used, the date each vial was opened and reconstituted, your weight, and any notes you want to bring to a clinician. Vial dates deserve care. The FDA recommends discarding a multi-dose vial within 28 days after first use, even if medication remains, because the risk of contamination rises after that time.[3] PepTrac lets you enter the reconstituted date for each vial, but it does not count down the 28 days or flag a vial, so check the date yourself. It keeps your dose history in one place and has a data export, so you can hand a clinician a clean record. It records what you enter and gives no advice on how long a cycle should be or when to stop. Those decisions belong to you and your prescriber.
Frequently asked questions
Does PepTrac tell me how long to cycle?
No. PepTrac records the on days, off days, and dose steps that you enter. It does not suggest a cycle length, a break, or a dose. Those decisions belong to you and your prescriber.
Can each compound have its own cycle?
Yes. On days and off days are stored per protocol, so each compound can follow its own pattern. The weekly grid on the Track tab shows every protocol side by side.
Does a cycle apply to semaglutide?
The Ozempic label describes once-weekly dosing on the same day each week, not a cycle with off days. PepTrac lets you leave on and off days blank, so every day counts as an on day.
Does the last titration step end?
No. The final step holds until you change the schedule. It does not loop back to the start or stop, so the dose stays at that step once its window is reached.
Does a break lower the level estimate?
Yes, if you do not log doses. The level curve counts only logged doses, so a break shows as a falling curve. The curve is an estimate with a range, not a lab result.
Sources
- DailyMed, National Library of Medicine (Novo Nordisk). Ozempic (semaglutide) injection prescribing information. Accessed October 3, 2026.
- DailyMed, National Library of Medicine (Eli Lilly). Mounjaro (tirzepatide) injection prescribing information. Accessed October 3, 2026.
- U.S. Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. Accessed October 3, 2026.
Written and maintained by the team that builds PepTrac. Every calculator on this site runs the same tested math as the app. Read how we research, cite, and update pages in our editorial policy.
