The normal length of menstrual cycle is about 28 days on an average; however this can differ quite a bit from woman to woman. Answer to the question, ‘how long is a menstrual cycle’ varies greatly from woman to woman. What is considered perfectly normal for one, may be quite abnormal for another. Anything from a 21 day cycle to a 35 days cycle can be considered normal, and various factors will impact this.

Length of Menstrual Cycle

Age of a woman

When a girl first starts to menstruate, she may have fairly irregular cycles or very long ones; as long as 45 days from the start of one period to the start of the next. This is because her hormones are still in the process of settling down and it may take a while for a fixed and predictable pattern to emerge.

Until such time the length of menstrual cycle can be unpredictable. Similarly when a woman approaches menopause or the end of her life’s fertile period, she will notice other changes in her menstrual cycle such as she saw during the beginning of her life’s fertile period.


The length of menstrual cycle can be influenced by heredity and a woman whose mother had a particular pattern of menstruation may have the same sort of pattern herself.


Excess stress, a life changing event, bereavement could change how long is a menstrual cycle for a given woman.

Hormonal Imbalance

Birth control methods, eating disorders, excessive exercising, obesity and hormonal imbalances due to other reasons can also alter length of menstrual cycle for women.

How long is a Menstrual Cycle?

We know that 28 days is considered the average duration of a menstrual cycle and cycles plus or minus 7 days (21 days or 35 day) may also be as normal. So some women have shorter cycles because this is normal for them and others have longer cycles because this is normal for their systems.

The length of menstrual cycle is considered normal if there is less than 8 days difference between her longest and shortest cycle. So if her shortest cycle is 25 days and her longest cycle is 32 days this is within the normal range of variation. If however the variation is between 8 or 20 days between the shortest and longest cycles, this is classified as moderately irregular and any variation of more than 21 days is considered very irregular.

How can you normalize and regularize a menstrual cycle?

To regularize an irregular menstrual cycle, make sure that you are not obese, because this can contribute to the hormonal imbalance resulting in irregular periods. Proper exercise and a healthy diet can help to lower negative impacts of being overweight as well as underweight.

Control stress and stop smoking because both these factors can disorder how long is a menstrual cycle. Starting on birth control pills can also help to regularize menses.

Herbal remedies such as wild yam, chaste tree, nettle, lady’s mantle, and so on can also help to regulate the length of menstrual cycle.