Red Tent PMDD estimates cycle day and current phase on Home from your logged period starts and cycle length. Learn how Day 1 is counted, how phase is assigned for the date in the header, and where both appear on the cycle ring and hormone chart.
What cycle day and phase mean on Home
- Cycle day — how many days into the current cycle the selected calendar day falls, starting at Day 1 on your period start.
- Current phase — which of the four cycle spans (Menstrual, Follicular, Ovulatory, or Luteal) the app assigns to that day.
- Date header — the ring and hormone chart both follow the calendar day shown at the top of Home, not necessarily today.
- Estimates only — numbers come from on-device models using your logs; they are not clinical timing or lab results.
How cycle day is counted
- Day 1 — the first day of bleeding you log as a period start. That calendar date is cycle day 1.
- Count forward — each later calendar day adds one (Day 2, Day 3, and so on) until the next logged period start begins a new cycle.
- Active cycle — the app finds the cycle that covers the Home date and counts from that cycle's start date.
- No number — when no cycle covers the selected date, the ring hides Day N until you log enough period history.
How the current phase is assigned
- Cycle length — for a finished cycle the app uses logged start-to-end days; for an ongoing cycle it uses your personal average length (or a 29-day default until enough history exists).
- Phase lengths — the four phases are split proportionally across that cycle length (see the cycle phases article for what each phase means).
- Match the date — when your cycle day falls within the effective cycle length, the app picks the phase whose date range contains the selected Home day.
- Beyond the cycle — when the day falls past the effective length, the app estimates phase and day from your average cycle pattern until you log the next period start.
- Ring and chart — both surfaces read the same cycle day and phase for the date in the header.
✦Phase and cycle day are on-device estimates from your period logs—they help you orient on Home, not confirm ovulation, bleeding, or a diagnosis.
On Home — cycle ring center
01
Date header
Scroll to the calendar day you want. The phase name and Day N in the ring center update to match that date.
02
Day
Shows your estimated cycle day (for example, Day 14) for the selected Home date when a cycle can be calculated.
03
MENSTRUAL
The current phase name appears in uppercase in the ring center—MENSTRUAL, FOLLICULAR, OVULATORY, or LUTEAL when the app can assign a phase.
04
Let us know
When the app cannot determine a phase for the selected date, the center label reads Let us know and Day N is hidden. Log period starts to restore cycle day and phase display.
Colored phase arcs, ring drag, and moon flip are covered in the Home cycle tracker article—not repeated here.
On Home — hormone chart accent
01
Cycle day line
A vertical accent crosses the hormone chart at your estimated cycle day for the selected Home date. It appears only when cycle day can be estimated.
02
Date header
Changing the Home calendar day moves this accent to the new day's cycle position. Curve shapes and legend details are in the hormone chart article.
What your period logs control
- Period starts — each logged start anchors a new cycle and resets Day 1. Ongoing logging from the + menu is covered in the Track Period article.
- Cycle length — completed cycles update your personal average; that average shapes phase splits and predictions for ongoing cycles.
- Next-event text — estimated next ovulation or period timing under the ring uses the same logged data; see the predictions article for that copy.
When phase cannot be shown
- Let us know — the ring center phase title when no active cycle covers the selected date or phase cannot be calculated.
- Missing Day N — without a calculable cycle day, the ring omits the Day line and the hormone chart hides its vertical accent.
- Restore display — log period starts (onboarding, Track Period, or Health import) so the app can anchor cycles and assign phases again.