Period Calculator
Predict your next period date and track your menstrual cycle.
The Period Calculator predicts your upcoming menstrual periods based on your cycle length and last period start date. It helps you plan ahead and notice any irregularities in your cycle.
Enter the day your last period started, your average cycle length, and your typical period duration. The calculator predicts your next three period start dates and estimates how many periods you have per year.
A normal menstrual cycle ranges from 21-35 days, with 28 days being the textbook average. Period duration typically lasts 3-7 days. Tracking your cycle helps identify patterns and irregularities to discuss with your healthcare provider.
Frequently Asked Questions
What is a normal cycle length?
Normal menstrual cycles range from 21 to 35 days. The average is 28 days, but many women have cycles slightly longer or shorter.
Why might my period be late?
Stress, weight changes, exercise, illness, hormonal changes, and pregnancy can all cause delayed periods. Consult a doctor if periods are regularly irregular.
How many periods does a woman have per year?
With a 28-day cycle, approximately 13 periods per year. Longer cycles mean fewer periods annually.