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Track your menstrual cycle, predict your next period and ovulation date, and log symptoms.
Period Tracker predicts your next 4 period start dates, ovulation days, and 6-day fertile windows using standard cycle length calculations (ovulation ≈ cycleLength − 14 days before next period), and lets you log daily symptoms and flow.
Predict your next 4 periods and ovulation dates, understand your cycle phases, and log daily symptoms.
Enter your last period start date.
Set your cycle and period length.
See predictions for the next 4 cycles.
Ovulation day estimated as cycleStartDate + (cycleLength − 14). Fertile window = ovulation − 5 days through ovulation + 1 day (accounting for sperm survival up to 5 days and egg viability 12–24h). Cycle phases use standard luteal phase of 14 days.
Predictions are estimates based on your average cycle length. Cycles vary due to stress, illness, and hormones.
The fertile window is roughly 5 days before ovulation plus ovulation day — about 6 days total.