Home Pregnancy Getting Pregnant How to Calculate Safe Period to Avoid Pregnancy Naturally?

How to Calculate Safe Period to Avoid Pregnancy Naturally?

How to Calculate Safe Period to Avoid Pregnancy Naturally?

Long before contraceptive methods were introduced, people relied on calculating ovulation days to know when to have safe intercourse and avoid pregnancy naturally. This is also known as the calendar method.  

Safe period to avoid pregnancy naturally – The menstrual cycle is commonly divided into three phases: the follicular phase (pre-ovulatory phase), ovulation, and the luteal phase (post-ovulatory phase). The infertility period depends on the lifespan of sperm and of the egg. To put it simply your infertile period is when there is no egg in your body because if there’s no egg, then there’s nothing for the sperm to fertilize.

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However please remember that your cycle can fluctuate because of reasons like stress and hormonal changes. These could cause your period to be delayed or come early in which case it becomes difficult to calculate safe days.

Calculate Safe Period to Avoid Pregnancy Naturally

To practice this method, you must first keep track of your period for at least six months to see whether its regular or not. These days there are several apps available on your smartphones which help you in keeping track of your infertile days.


You just need to input the date your period starts and ends and the app calculates your safe days to avoid pregnancy naturally. Some of the popular apps are:

  1. Safe Sex Calculator

  2. Flo Period & Ovulation

  3. Cycles

  4. Dot

Now let’s come to an example. Day 1 is the first day of your period. Count the number of days from Day 1 till the start of your next period. This is your cycle length. Do this over 6 months. Then take the shortest cycle from among these 6 and subtract 18 from the number of days. For instance, if your shortest cycle was 28 days, subtract 18 from it so 28-18=10. Now count 10 days from Day 1 of your period. This marks the START of your fertile period.

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Similarly to find the last fertile day, take the longest cycle from the past 6 months and subtract 11 from the total number of days. For instance, if your longest cycle was 30 days then subtract 11 from it so 30-11=19. Count this from Day 1 of your period. This will be your LAST fertile day.

Avoid Pregnancy Naturally

In the above example, Day 10 to Day 19 are the fertile days. This means that it’s relatively safe (not completely) to have unprotected sex on all other days of the cycle.

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Do remember that if your cycle is consistently less than 27 days then this method is not advisable. Also, remember the cardinal rule- if you have sex, you can get pregnant! It’s always better to supplement the safe days’ method with another form of contraception to be doubly sure.