Period Calculator
Next Period Predictor
Predict when your next period will start
Cycle Regularity Check
Assess how regular your menstrual cycles are
Formula
Next Period = Last Period Start + Cycle Length | Ovulation ≈ Next Period - 14 days | Regularity = Max Cycle - Min Cycle variance
Frequently Asked Questions
How long is a normal menstrual cycle?
A normal menstrual cycle lasts between 21 and 35 days, with the average being about 28 days. The cycle is counted from the first day of one period to the first day of the next period. Periods typically last 3-7 days.
What can cause an irregular period?
Common causes include stress, significant weight changes, excessive exercise, hormonal imbalances (PCOS, thyroid issues), perimenopause, starting or stopping birth control, pregnancy, breastfeeding, and certain medications.
When should I see a doctor about my period?
See a doctor if your periods are consistently shorter than 21 days or longer than 35 days, if you bleed for more than 7 days, if you soak through a pad or tampon every hour, or if you experience severe pain that interferes with daily activities.
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