Calendar
What each color means on the MiniCycle period calendar
Open MiniCycle and a month can show five or six kinds of marks at once: pink bands, a blue stretch, a small diamond, a dot, a capsule. None of it needs memorizing once you know the one rule the calendar follows. Solid marks are records you made. Striped marks are estimates the app computed. Everything else is a shape with one job. Here is the full legend, and where each mark gets its dates.
Start with the rule: solid is a record, striped is an estimate
A period you logged appears as a solid light-pink band across its days. A period the app expects appears in the same pink, but hatched with diagonal stripes. The legend under the calendar names the two plainly: Period and Expected.
The two behave as differently as they look. A record never moves unless you edit it. An estimate is recalculated whenever you save a new start date, and it can be wrong in either direction. Drawing them identically would lend predictions a certainty they have not earned, so the stripes keep the difference visible at a glance.
Where do the striped period days come from?
The expected period is placed one cycle length after your last recorded start. For the cycle length, MiniCycle looks at up to your latest 12 period records; once there are at least 10 measured intervals, it drops one shortest and one longest, then takes the median. With less history it works from a 29-day default, and a manual setting between 21 and 42 days overrides all of this.
When the period actually arrives and you log it, the striped band gives way to a solid one anchored on the real date. An analysis of 612,613 real-world cycles found that cycle length varies from month to month for most people, which is why the stripes never claim to be more than a current best guess.
The sky-blue band is the fertile window
Sky blue marks the estimated fertile window, from 5 days before the estimated ovulation day through 1 day after it. The span is grounded in the work of Wilcox and colleagues, who defined the fertile days as the five days before ovulation plus the day itself, because sperm can survive in the body for days while the egg lasts roughly 12 to 24 hours. MiniCycle adds one day after as a calendar margin, not a medical claim.
Look a few months ahead and the blue band changes texture. The window tied to your current cycle is solid; windows past the next expected period are striped, because each further cycle stacks one more assumption about a length that has not happened yet. Past windows, computed from the actual intervals between your recorded periods, stay solid.
The small marks under a date
Three shapes can sit under a date number. A deeper-blue diamond is the estimated ovulation day, counted backward from the next expected period using a luteal phase estimate clamped between 9 and 14 days rather than a fixed 14. A purple dot is a sexual activity record. A short gray capsule means the day has a note.
Today is the one date drawn over everything else: a white number on a red circle, with the small marks set aside for the day. The records are still there. Select the date and the day's details appear below the calendar.
Why the meaning never rides on color alone
Accessibility guidance is blunt about this. The W3C's WCAG criterion on the use of color requires that color not be the only visual means of conveying information, and its suggested techniques include pairing color with pattern. That is the design MiniCycle follows: records and estimates differ by fill versus stripes, not by hue, and ovulation, activity, and notes each get their own shape.
The same decision matters in dark mode, where every tint sits on a dark background at lower opacity, and for anyone who finds pink and blue close in lightness. If the hues ever read ambiguously, the pattern and the shape still answer the question the calendar exists for: which days are records, and which are estimates.
What a colored day cannot tell you
No mark on the calendar is a measurement. The app never knows whether ovulation happened; it places a diamond by arithmetic. In the Wilcox study, even among women with regular 28-day cycles, only about 10% ovulated exactly 14 days before the next period, and the time from ovulation to the next period ranged from 7 to 19 days. A calendar estimate cannot pin a spread like that to one certain day.
So the blue band is not contraception, the diamond is not a fertility verdict, and a striped pink day is not a deadline your body agreed to. The marks are reference information for planning. When the calendar and your body disagree, the body wins, and logging what actually happened is how the calendar catches up.
Hiding the marks you do not need
The legend row itself can be switched off in Settings once you know the colors and want a quieter screen. The marks on the calendar stay; only the explanation row goes away.
Sexual activity has a stronger option. Hide it, and the purple dots disappear from the calendar and the legend entirely while the records stay on your device. Turning the display back on requires Face ID on a real device, so a briefly borrowed phone does not casually reveal it. The records themselves are stored locally by default, as the privacy policy describes.
Frequently asked questions
A day falls inside both a pink band and the blue window. Which wins? The period band is drawn, since a recorded or expected period is the stronger signal for that day. The ovulation diamond still appears under the date if it lands there.
Why is there no diamond or dot on today's date? Today is marked by the red circle, which takes the cell for the day. Select the date and the day's details appear below the calendar.
Why is there no color for so-called safe days? Because a calendar cannot promise one. In the Wilcox data, women had at least a 10% chance of being in their fertile window on every day between days 6 and 21 of the cycle. MiniCycle marks an estimated window and deliberately leaves contraception decisions to methods built for them.
Reading a month in ten seconds
Solid pink tells you what happened. Striped pink tells you what the app expects next. Blue marks the span where conception is most plausible by the calendar's estimate, the diamond is the single most uncertain mark on the screen, and the dots and capsules are simply your own annotations coming back to you.
Every one of those marks hangs off the start dates you save. Log the start on the day it happens, and the bands, the diamond, the reminders, and the widget all stay anchored to the same reality with no further effort.
MiniCycle is built for a clean iPhone period calendar, local records, simple statistics, and a home screen widget.
View on the App StoreReferences
- W3C Web Accessibility Initiative. Understanding Success Criterion 1.4.1: Use of Color.
- Wilcox AJ, Dunson D, Baird DD. The timing of the fertile window in the menstrual cycle. BMJ. 2000.
- Bull JR, Rowland SP, Scherwitzl EB, et al. Real-world menstrual cycle characteristics of more than 600,000 menstrual cycles. npj Digital Medicine. 2019.
- MiniCycle Privacy Policy.