Menstrual calculator: calculate your next period

Menstrual calculator: calculate your next period


Women who have a regular menstrual cycle, that is, it always has the same duration, can calculate their menstrual period and know when the next period will come.

If this is your case, enter the data into our online calculator and find out when your next periods will be:

What is the menstrual period?

The menstrual period represents the number of days from when menstruation begins until it disappears completely, which generally lasts approximately 5 days, but which can vary from one woman to another.

Menstruation marks the beginning of the menstrual cycle and happens about 14 days after ovulation, in women with a regular cycle.

Understand better how the menstrual cycle works and when your period starts.

Consult your nearest gynecologist, using the following tool, to clarify any doubts about the menstrual cycle:

Taking care of your health has never been easier!

What is the point of knowing the day of your period?

Knowing what day the next menstruation will be is useful so that the woman has time to prepare for that moment, as she may need to adapt her daily routine, in addition to helping with scheduling gynecological exams, such as a pap smear, which should be done outside of the menstrual period.

Knowing when your next period will also help to avoid unwanted pregnancy, as this is considered a woman’s least fertile period, especially in women with a regular cycle.

What if you don’t know when your last period was?

Unfortunately, there is no way to calculate your menstrual period without knowing the date of your last period. Therefore, we recommend that women take note of the day of their next menstruation, so that, from there, they can calculate their next periods.

Does the calculator work for irregular cycles?

Women who have an irregular cycle have greater difficulty knowing when their menstrual period will be. This happens because each cycle has a different duration, which means that the day of menstruation does not always occur with the same regularity.

Since the calculator works based on the regularity of the cycle, it is very likely that the calculation of the next menstrual period will be wrong in the case of women with an irregular cycle.

Check out another calculator that can help in the case of an irregular cycle.

We regularly update our content with the latest scientific information, so that it maintains an exceptional level of quality.

  • SchmaLeNBEGER, KM; et al. How to study the menstrual cycle: Practical tools and recommendations. Psychoneuroendocrinology. 123. 104895, 2021
  • CRICHLEY, HOD; et al. Physiology of the Endometrium and Regulation of Menstruation. Physiol Rev. 100. 3; 1149-1179, 2020
  • REED, B. G.; CARR, B. R. IN: FEINGOLD KR, ANAWALT B, BLACKMAN MR, ET AL., EDITORS. ENDOTEXT (INTERNET). SOUTH DARTMOUTH (MA): MDTEXT.COM, INC. The Normal Menstrual Cycle and the Control of Ovulation. 2018. Available at: <>. Accessed on 21 Sep 2023