Menstrual cycles change over time and with diet, age, childbirth and certain health conditions. Keeping track of your cycle days helps you know when you can expect to have your period. It also helps you know approximately when you will ovulate so you can choose to try to conceive or choose to avoid becoming pregnant. Counting cycle days is most effective when you do it for a few months. The longer you do it, the more familiar you will be with your own reproductive cycle and the more accurate your information will be.
Step 1
Circle the first day of your menstrual period on your calender. The day you get your period is cycle day No. 1. Circle each day on the calender that you're on your period to get an idea of your average menstrual period length.
Step 2
Count 14 days from the first day of your period to get to your estimated ovulation day. This date is based on the assumption that your menstrual cycle is 28 days long, as this is the average cycle length. According to Brown University Health Education, your cycle may be longer or shorter than 28 days, and you may not ovulate exactly in the center of your cycle. Look for signs such as egg-white cervical mucous and a one-degree increase in basal body temperature to get a better idea of when you ovulate.
Step 3
Count and mark three to five days days before and three to five days after your ovulation date as potential fertile days. This is because sperm can live in your vagina for three to five days, according to the University of Michigan Health System.
Step 4
Count 28 days from the date of your first period or 14 days from your ovulation date. This will likely be the last day of your menstrual cycle. You can expect to get your period around this time. The more time you spend recording and numbering your cycle days, the more reliably you will be able to predict menstruation.
Step 5
Mark the first day of your next period on your calender as day one of your new cycle. Count the actual days from the beginning to the end of your previous cycle and this will tell you that month's cycle length. Plan the current month by subtracting 14 from the total number of cycle days in the previous month. This is because, according to Brown University Health Education, ovulation is most likely to occur 14 days before menstruation regardless of how long the cycle is. Now that you have a cycle length to work with, you can begin using your calculations to more accurately predict fertility.
Things You'll Need
- Calendar
