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Calendar Method Contraception

 Quick Facts

  • It may appeal to you even if you have religious objections to using medical contraceptives.
  • Can be stopped at any time.
  • It makes you self-aware of your body and periodic cycles.


This method is about 76 percent effective in preventing pregnancy. You should closely track your fertility to increase effectiveness.

Calendar method 76%

Key Benefits 

  • There are no medical side effects.
  • It is an inexpensive and safe way to prevent pregnancy.
  • There are no medical contraindications.

What is a Calendar Method of Contraception?

The calendar method, also called the calendar rhythm method, is a natural family planning method. It is based on avoiding sex during the fertile phase in the menstrual cycle, and the fertile phase is when fertilization can occur, resulting in pregnancy.

      Research has found that you may be most fertile for less than six days of your cycle. This period coincides with the process of ovulation. Ovulation is the release of an egg from the ovary. Once an egg is released from the ovary, it enters the fallopian tubes, where fertilization will occur. Without impregnation, the egg travels through the tubes and dies. This process takes around 24 hours, and it’s solely within these  24 hours that fertilization of the egg can occur. However, sperm cells will survive within the fallopian tubes for up to 5 days following ejaculation. It suggests that if a lady has unprotected sex within the five days before ovulation, there’s an opportunity that sperm is still alive and can fertilize an egg. Therefore, the lady is considered to be fertile for six days instead of 24 hours.

Calendar method contraception
Calendar method contraception

How to use calendar method contraception correctly?

  • Record the duration of six to twelve of your menstrual cycles. Use a calendar to write down the number of days in each cycle. The menstrual cycle is deemed to start from the first day of your period and end before the first day of your next period.
  • Monitor the length of each menstrual cycle every month and always use data from the most recent six menstrual cycles to calculate the fertile days, as explained above. Update your calculation each month.
  • Find the length of your shortest menstrual cycle. Subtract 18 from the total number of days in your shortest cycle. This number denotes the first fertile day of your cycle. For example, suppose your shortest cycle is 27 days long, subtract 18 from 27 — which equals 7. The first day of menstrual bleeding is supposed to be the first day of your cycle, and the seventh day of your cycle is thus the first fertile day.
  • Find the length of your most extended menstrual cycle. Subtract 11 from the total number of days in your most extended cycle. This number denotes the last fertile day of your cycle. For example, suppose your most extended cycle is 31 days long, subtract 11 from 31 — which equals 20. The first day of menstrual bleeding is supposed to be the first day of your cycle; thus, the 20th day of your cycle is the last fertile day.
  • Do not have sex during fertile days or use another contraceptive every month.


  • No side effects.
  • There is no need to visit a doctor.
  • Working together on birth control may bring you and your partner closer.


  • It requires that you have sex, not to do sex for several days in a month.
  • Efficacy is lower than other reversible and permanent methods
  • Work-related and physical stress can affect monthly periods, making knowing your fertile days tough.
  • No protection from HIV and other Sexually Transmitted Infections
  • No systemic side-effects
  • Very little or no cost
  • There is no adverse effect on breast milk

Essential Tips

  • Certain apps can help you track your periods. To use these apps, you must fill in the information correctly in the app details.
  • It will be better to talk with a doctor, nurse, or healthcare provider  to learn how to use it correctly.
  • The best way to use the calendar rhythm method is to combine it with other contraceptive methods, such as the temperature and cervical mucus. Each method relies on different signs to calculate your fertile days, so using them together can make contraception more accurate.

Recommended to use if

  • If you have regular menstrual periods.
  • You and your partner are ready to avoid vaginal sex or to use another kind of contraceptive around your fertile days.
  • You have the time, passion, and discipline to chart your cycle

Not Recommended if

  • You experience irregular periods or do not have periods
  • If you have had a baby recently
  • You are breastfeeding
  • You find it hard to avoid sex on your fertile days
  • Was just on a hormonal method of birth control and had stopped recently
  • You have irregular cycles or are on medications that affect cycle length, e.g., lithium, some anti-depressants, anti-anxiety drugs, certain antibiotics, and anti-inflammatory drugs.

In Short

The “Calendar method”  is a form of periodic abstinence, and it can be an effective prevention against pregnancy, although it can be hard to practice.

  1. AIIMS
    Fertility Awareness-Based Methods
  2. Wiley Online Library
    Fertility Awareness Methods
  3. Cleveland Clinic.Rhythm Method
  4. The Geneva Foundation for the Medical Education and Research
    Natural Contraceptive Methods




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