Part of the Loopa iOS app guide.
The cycle calculator projects your next six periods from three numbers: the first day of your last period, your cycle length and your period length. You don't need two logged cycles first, and nothing you enter in it is saved. It is in the iPhone and Android apps; the browser Cycle page does not have it.
Calendar estimates, not medical advice, and not a contraceptive method.
Where it is
Open the Cycle screen (Health tab, The Log, Cycle) and tap the Cycle calculator row under the Estimates card. The row reads "Project the next six periods from your own average." once you have logged cycles, or "Work out the next six periods without waiting to log two cycles." before. See Cycle tracking for turning the Cycle tracker on.
Which plan
The cycle calculator is part of Loopa Premium, like the rest of cycle tracking. Every new account starts with 14 days of Loopa Premium; see Your first 14 days.
Your cycle
The Your cycle card holds the three inputs. When it opens, Loopa fills them in from what you have logged, and the line under them reads "Working it out…" and then, if it used your history, "Cycle length filled in from your own" number of "logged cycles."
- First day of your last period ("Day 1 is the first day of bleeding"). Today or earlier. It starts on your last logged period start, or today.
- Cycle length ("First day to first day"). From 15 to 90 days. It starts on your own average, or 28.
- Period length ("Days of bleeding"). From 1 to 14 days. It starts on 5.
Change any of them and the projection below updates. Your logged history is not changed.
Next period
The headline is the date your next period is most likely to start. Under it:
- "Give or take" so many days, "from how much your cycles vary." The margin is half the range of your logged cycle lengths.
- Or, when your logged cycles have all been the same length, "Your cycles do not vary, so this is the date your average points at."
The fertile window
Each projected cycle shows when you are most fertile, unless your cycle length varies by 7 days or more. Then the calculator shows no fertile window and says why: "Your cycle length varies by about" so many days, "which is too much for a fertile window to mean anything. We would rather show you nothing than show you the wrong six days."
The next six cycles
The chart titled The next six cycles draws one band per cycle, with a key: Period, Could start here and Most fertile. The pale band shows when each period could actually start, and it widens further out, because every cycle adds its own margin of error to the one before it.
Under the chart, each projected cycle is listed as Period 1 to Period 6 with its dates, "Most fertile" and its dates (when shown), and "Could start anywhere from" one date to another.
When your average is outside 24 to 38 days
If your average cycle is shorter than 24 days or longer than 38, the calculator says so: "A" so many "-day cycle is outside the 24 to 38 days Mayo Clinic and ACOG call typical. Worth mentioning to a doctor. It does not mean anything is wrong: plenty of people sit outside the average, and we cannot tell you which you are." See Cycle tracking for the list of things worth raising with a healthcare professional.
The disclaimer
The bottom of the screen reads "Calendar estimates, not medical advice, and not a contraceptive method. Nothing here is saved." Nothing in the calculator should be used to prevent or plan a pregnancy.
See also
