Health & Wellness
Menstruation & Ovulation Tracker
Calculate your next period, highly fertile days, and estimated ovulation date based on your cycle history. Free and perfectly private.
Cycle Details
Your Next 3 Cycles
How We Predict Your Cycle
This calculator uses standard medical formulas to estimate your future menstrual cycles. Your next period is calculated by adding your average cycle length to the start date of your last period.
Ovulation typically occurs about 14 days before the start of your next period. Your "fertile window" is the 5 days leading up to ovulation, plus the day of ovulation itself. This is the time during your cycle when pregnancy is most likely to occur.
Privacy First
Health data is incredibly sensitive. Unlike many period tracking apps that upload your cycle data to the cloud, this calculator runs 100% locally in your browser. We do not store, track, or harvest any information about your menstrual cycle.