How to Calculate Your Safe & Unsafe Periods

Women have been calculating their safe period or infertile days to avoid pregnancy for thousands of years. You can only count on using this natural safe period method if your periods are regular and you do not miss any menstrual cycles. As a general rule, in the last six months if your period occurred between days 26 to 30 of your period and lasted no more than eight days, you can use the safe period method. It is important to remember that ovulation usually occurs between day 12 to 19 of a woman's cycle and that sperm can live for three to five days in a woman's body.

Things You'll Need

• Calendar
• Pen

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Instructions

• 1

  Take six months to make certain that your period is regular each month and lasts less than eight days.

• 2

  Mark on your calendar day one to seven as infertile or safe days if you have a regular menstrual cycle that lasts from 26 to 31 days.

• 3

  Take the shortest cycle (26 days) and subtract that from 18 days to get the eighth day and take the longest cycle of 31 and subtract by 10 for day 21. This would mean day 8 to 21 is a fertile and unsafe period to have sex. Day 1 to 7 and day 21 through the rest of your cycle are safe periods of infertility to have sex.