How long does a typical menstrual cycle last?

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Front view anatomical diagrams of the male and female reproductive systems, with labeled organs including penis, testis, prostate gland, uterus, ovary, and vagina. — human reproductive system Organs and structures of the male and female reproductive systems.

A typical menstrual cycle lasts an average of 28 days, though a normal range is generally considered to be between 21 and 40 days.12

The cycle is measured from the first day of one menstrual flow to the first day of the next. While 28 days is the standard reference, cycle lengths can vary between individuals and even within the same person, with variations being most common in the years following menarche and leading up to menopause.123