📆 Period Calculator
Enter your last period date and cycle length to predict upcoming periods
How Does the Period Calculator Work?
This calculator predicts your upcoming period dates by adding your average cycle length to the start date of your last period. For example, if your last period started on April 1st and your cycle is 28 days, your next period is predicted to start around April 29th.
Most menstrual cycles range from 21 to 35 days, with 28 days being the average. Cycle length is measured from the first day of one period to the first day of the next. Tracking your cycle over several months gives you the most accurate picture of your personal patterns.
Stress, illness, changes in weight, and hormonal fluctuations can all affect your cycle length. If your period is consistently irregular or you have concerns, consult your OB-GYN or healthcare provider.