Rhythms, logged softly

Your cycle, gently mapped

Drop in the last few first-days of your period and we'll find the average cadence and what's probably next.

One date per line, in YYYY-MM-DD format. Add three or more for a better picture.

A note on the math

We use the average gap between your logged period-starts. More data — three, four, six cycles — gives a gentler, more reliable prediction. Cycles that swing wildly (say, more than seven days of variation) are worth mentioning to a clinician, especially if you're trying to conceive or noticing new patterns.