What is a normal menstruation cycle?

Varies. . The menstrual cycle is from day 1 of bleeding to day 1 of the next time of bleeding. Although the average cycle is 28 days, it is normal to have a cycle that is shorter or longer. More frequent than every 21 days is too much, and later than every 35 days is too few. Normal menses lasts 5-7 days. Any bleeding that is heavy abd bothersome to a patient may need evaluation.