How to track your period—without an app

To have a period is to live in constant fear of ruining your best pair of underwear or making a spectacle of yourself the day you decide to wear white pants. And that’s just the least important reason to keep an eye on your cycle.

There are many period apps out there that promise to make your life easier in this regard, but you may not want to rely on it. Fortunately, tracking menstrual cycles did not start with the smartphone era, and you can always start tracking your body using the good old calendar method.

Research has found that what we understand as a healthy menstrual cycle differs depending on where in the world you are. In the US, a healthy cycle is anywhere between 21 and 35 days, has a period that usually lasts between three and seven days, and happens monthly up to two days after the last one. Any drastic variation outside of these parameters requires a visit to the doctor, but since all bodies are different, some irregularities may be completely normal.

You can divide a menstrual cycle into two parts — the pre-ovulation stage or follicular phase, and the post-ovulation stage, or luteal phase. These two episodes are separated by ovulation, the main event in each cycle where the ovary releases an egg into the fallopian tube.

In the follicular phase, the egg ages in a follicle within the ovary. Once ready, estrogen levels signal to the brain that it’s time for the egg’s debut in society, and the noggin ‘respond by releasing luteinizing hormone to activate ovulation. The egg is now free to try to fulfill its purpose.

The empty follicle that remains in the ovary changes into the progesterone-releasing corpus luteum. This small structure is the key to understanding your specific menstrual cycle, as it is one of the only elements in this whole process that remains mostly constant for all menstruating people. If the ovum does not find a companion to join in the dance of life, the corpus luteum dies after 12 to 14 days, which suddenly reduces the supply of progesterone and causes the secretion of the uterine lining, also known as your period .

Now that you understand how the menstrual cycle works, go ahead and write down the first day of your period — you can use a digital or analogue calendar, your planner, or even a piece of paper. Keep in mind that the first day of your cycle is the first day you have full-blown bleeding — spotting does not count.

Starting on the first day of your period, go back 14 days on your calendar. This is your ovulation day — tick it off. Knowing how long it takes your body to ovulate will help you determine when you will be at your most fertile, an important piece of information that, depending on how you use it, will help you conceive or it completely avoid.

Finally, write down details about each day of your period. Take note of the amount and color of your flow, plus any other symptoms such as soft breasts, back pain, headaches, moodiness, high sex drive and low energy. If you monitor symptoms throughout the rest of your cycle, you will eventually find patterns that will help you project ovulation, premenstrual syndrome, and, of course, your period.

This is why it is important to spend at least five months collecting as much data as possible about your menstrual cycle before you can make any projections. The results will be just as good as the data you collect, so the more details you write down, the better.

Also keep in mind that just as a period app may not tell you exactly when you are likely to get pregnant, the calendar method will also not give you a high level of accuracy. If you are monitoring your period as a natural birth control method, know that this technique is about 76 percent effective, and you may want to supplement it with other types of contraceptives, such as condoms, cervical mucus detection or basal temperature during your fertile window.