cycledot++

CycleDot is the simple, private period predictor. Tap the day your period starts and CycleDot learns your average cycle length and tells you roughly when the next one begins. A clean calendar shows your past starts and the predicted date, with a current cycle-day count. No account, no sign-up, no ads, and no data ever leaves your phone. Just the one thing you actually want: when is it likely to start. Unlike the big cycle apps, CycleDot collects nothing and costs a dollar.