How to Calculate Safe Days to Avoid Pregnancy

How to Calculate Safe Days to Avoid Pregnancy

When Can I Have Sex And Not Get Pregnant?


You are old enough for sexual intercourse but need to know how to calculate your safe days for not getting pregnant. You might have just had intercourse and want to be sure you did it on a safe day for not getting pregnant. Or you may be seeking “how to calculate safe days for not getting pregnant” because you need a break with making babies.

What is a safe day for not getting pregnant?


A safe day or safe days are days that a woman can have unprotected sex without the risk of getting pregnant. They are days within a woman’s menstrual cycle when her eggs are not available to be fertilized by a sperm.

When is a woman most likely to get pregnant?


The days a girl is most likely to get pregnant are around midway between her periodic bleeding. That’s when she is said to be in ovulation. Ovulation is when an egg travels from the ovaries through the Fallopian tubes to the womb. It is only during ovulation that fertilization/impregnation can occur.

Of course, having sex 4 days before ovulation can still result in a pregnancy as sperms can survive in a woman for up to 5 days after sex.

Calculating your safe days for not getting pregnant is really about knowing the days that your eggs are not available for fertilization. You know by now that getting pregnant is not possible if sperms do not come in contact with your eggs.

The whole idea behind how to calculate safe days for not getting pregnant therefore is to have intercourse on days that your eggs aren’t available for fertilization. This entails having an understanding of your menstrual cycle.

A woman’s menstrual cycle begins from the first day of seeing her period (menstrual bleeding) to the 1st day of the next period (menstrual bleeding). The menstrual cycle takes an average of 28 to 32 days for most women.

How to know the calendar of your menstrual cycle


To know how to calculate safe days for not getting pregnant;
  • Take note of the first day of your period (day 1).
  • Then note the first day of your next period.
  • Count how many days you have between the first days of each period.
  • You must take note of at least 6 cycles to get an accurate result.

Let me give you a practical illustration with the table below:


First Day of PeriodNumber of Days in Cycle
Jan 1
Jan 3029 days
Feb 2929 days
Mar 2929 days
April 2729 days
May 2326 days
June 2128 days
July 2130 days


Your safe days for not getting pregnant are calculated by counting:


➧ The first seven days of your menstrual cycle. That is counting 7 days from the first day you see your period and
➧ From the 21st day of your menstrual cycle to the end of that cycle.

Therefore, from day 1 to 7 of your menstrual cycle are safe to have sex and not get pregnant. Then day 21 to the rest of the cycle, are also safe days you can have sex without worrying about getting pregnant.

An illustration of safe days to have sex in a 30-day cycle

An illustration of safe days to have sex in a 30-day cycle


Period Calculator


There is an app that can help you track your menstrual cycle without your doing all the complex calculations.

Click here to use this app: https://always.com/en-us/period-calculator

Safe period calculator.

An app has been developed that can help you do the complex calculation. To use this app, click this link: https://safeperiodcalculator.com/


How to prevent pregnancy after sexual intercourse?


(Plan B)


Just in case you’ve had unprotected sex within the last three days, there is a medication that you can use to prevent pregnancy after intercourse. It’s called “Plan B” and is available over the counter at almost all drug stores. Plan B is about 95% effective in preventing pregnancy if taken within 24 hours of having sex.

If you take it within 72 hours after sex, Plan B reduces the risk of pregnancy by about 89%. It works by delaying ovulation, stopping fertilization of an egg, and preventing implantation.

Can I get pregnant on the last day of my period?


It is possible but very unlikely. Like I mentioned earlier, a menstrual cycle is the number of days between the first day of one period and the first day of the next period. Ovulation usually takes place between 7–19 days after a person’s period ends. That being the case, it is very unlikely that one can get pregnant during her period or even a day after her period.

Can I get pregnant 2 weeks before my period?


It all depends on whether the woman had sex anytime within 5 days of ovulation. If a woman’s menstrual cycle is irregular, it becomes difficult to determine when ovulation occurs.

However, if you had sex anytime within 5 days to ovulation, of course, you can get pregnant.
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