Tracking your period takes exactly one habit: log the first day of full flow each time it starts. This page turns that log into your average cycle, regularity check, and next-period prediction — stored only in this browser, on this device.
Because a dated log turns “my periods feel off” into evidence. Clinicians treat the cycle as a vital sign (ACOG Committee Opinion 651), and many people guess without a record:
Write down day 1 — the first day of full flow, not spotting — every time. Each new date unlocks more of the arithmetic:
Nothing to calculate yet; the log just remembers it.
Jun 3 is day 1, so Jul 2 is the next day 1 — 29 days later.
Gaps 29 and 32. A usable first average.
Gaps 29, 32, 28, 31. Spread 4 describes these four intervals; FIGO’s regularity parameters consider a year of cycles.
Oct 1 + 30 days. Every new entry updates this.
From the stats card you can send your numbers to the late period calculator or cycle length calculator without retyping.
Start dates drive every prediction; the rest helps a clinician see the pattern. This tracker stores dates only, so keep the extras alongside it:
| Start date | Days of bleeding | Flow | Pain (0–10) | Other notes |
|---|---|---|---|---|
| Aug 31 saved here | 5 | heavy day 1–2 | 4 | started new pill |
| Oct 1 saved here | 6 | light | 2 | spotting Sep 29 |
Prefer paper for everything? The printable period tracker has these columns built in.
Export saves the start dates you recorded, not a forecast. The CSV contains one column, period_start, with a date in YYYY-MM-DD format on each row.
Use the button above after adding your dates. Keep the downloaded file somewhere you control.
Open the CSV in Excel, Numbers or another local spreadsheet. If dates look different, choose a date format or use the text/CSV import option; the file keeps the YYYY-MM-DD values.
Use the spreadsheet’s Print command. This tracker has no separate Print button and no CSV import; to move the log into this tracker on another device, re-enter the start dates.
period_start
2026-06-03
2026-07-02
2026-08-03Demo CSV: start dates only. End dates, flow and symptom notes are not collected by this tracker. For a blank paper log with those fields, use the printable period journal.
Spreadsheet instructions: Microsoft’s text/CSV guide. Opening the file locally does not add an import or sync feature to this tracker.
In this browser, on this device — not on any server of ours. Here is every path your dates can take:
opc-tracker — no account, no server copyThe trade-off is no cross-device sync: switching devices means exporting and re-entering. Full details, including what the Google AdSense script receives, are in the privacy policy.
Bring the log to an appointment if it shows any of these (FIGO thresholds for adults; for teens, cycles of 21–45 days are normal in the first years — ACOG 651):
Log the first day of full flow each time. Cycle lengths are the gaps between those dates; the average is their mean. This page automates the arithmetic and keeps the log on your device.
Only in your browser's local storage, on your own device. The site never receives your dates; clearing site data deletes the log permanently.
Two start dates give one interval; three dates give two. Every additional start date lets you compare another gap. The mean summarizes the entries saved here; a short log does not establish year-long regularity.
Yes. Export CSV downloads your recorded start dates in the period_start column. Open the file in a spreadsheet to print it or save a PDF. It contains no symptom notes or end dates.
Use an entry’s Delete button, or Delete entire log and confirm. This removes the saved entries in this browser. CSV files you already downloaded, printed copies and records in another browser remain until you remove them separately.
No. Export CSV saves a copy of your start dates. This tracker has no CSV import: on another device, open that file for reference and re-enter the dates. Exporting does not sync or change the log on another device.
Yes — irregular cycles benefit most from tracking. Watch the shortest/longest spread; beyond about 7–9 days, the irregular period calculator fits you better than a single average.
Marking period start dates on a calendar and counting the gaps — the oldest method there is. This tracker is that method with the arithmetic automated.
Your cycle is a health signal clinicians treat as a vital sign (ACOG Committee Opinion 651) — a log turns “my periods feel off” into dates a doctor can act on. It’s also practical: knowing your window lets you plan travel, supplies and downtime around up to 8 days of flow (FIGO). And irregular cycles are common — 14–25% of women have them (NICHD) — so many people are guessing without a log.
Book a visit if your log shows: cycles consistently shorter than 24 or longer than 38 days (FIGO adult range); bleeding lasting more than 8 days; 90 days with no period (secondary amenorrhea); or a year-over-year spread beyond 7–9 days. For teens: cycles of 21–45 days are normal in the first years, but no first period by age 15 warrants evaluation (ACOG 651).
Because ovulation shifts, and the prediction is only as stable as your ovulation day. In 600,000+ real cycles the luteal phase held at 10–15 days while most variation came from the follicular phase (npj Digital Medicine, 2019). A prediction assumes this cycle matches your average; when ovulation runs early or late, the period follows. The log’s value is the history, not any single predicted date.
Three things clinicians ask about that dates alone don’t capture: flow (light/normal/heavy and how many days — ≤8 days is the FIGO normal limit), cramps or pain that disrupts your day, and mood changes that repeat in the same cycle phase. This tracker stores dates; jot the rest in the same place each cycle — a note on your phone works. Patterns across 3+ cycles are what turn symptoms into useful information.
Yes — no account and on-device storage suit a first tracker, and early cycles need patience rather than prediction: teen cycles of 21–45 days are normal while the cycle matures (ACOG Committee Opinion 651), so expect wide swings in the first years. One flag: no first period by age 15 is the standard point for medical evaluation.