Period Calculator

Your next period is expected to start on the day after your cycle length from your last period's first day. For a 28-day cycle that started March 1, your next period would be expected around March 29.

Normal menstrual cycles range from 21 to 35 days, with 28 days being the average. Cycles that are consistently shorter than 21 or longer than 35 days may warrant a conversation with your healthcare provider.

Common causes besides pregnancy: stress, weight changes, excessive exercise, illness, travel, hormonal changes, and starting/stopping birth control. Occasional irregularity is normal, but consistently irregular periods should be discussed with a doctor.