Menstrual Cycle Length Calculator

Cycle length is the number of days from the start of your last period to the day before your next period started.

If your cycle length varies significantly month-to-month, use an average of the last 3-6 cycles for the best prediction results.

Yes. Knowing your cycle length allows you to accurately calculate your fertile window and ovulation day. For example, in a 32-day cycle, ovulation typically occurs around day 18 (32 minus 14-day luteal phase).

Consult a healthcare provider if your cycle is consistently shorter than 21 days or longer than 35 days, if you experience very heavy bleeding, or if your cycle length varies by more than 7-9 days month to month. These may indicate hormonal imbalances or conditions like PCOS.

Yes. Teenage cycles are often longer and irregular (up to 45 days). Cycles typically become more regular in the 20s and 30s, averaging 28 days. As you approach perimenopause (typically mid-40s), cycles may become irregular again. This information is for educational purposes and is not medical advice.

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