How to Use Period Calculator

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Are you having problems determining the dates for your monthly period? If so, you should know that a period calculator will help you to estimate the date for your next menstruation. This calculator can give estimated details including the starting dates for your periods over the next twelve months or the next year.

You might be thinking that you don’t need to know your period date for every month, but imagine how this information will come in useful if you are actually planning to conceive. The calculator is very simple to use. You are only required to input the starting date for your last period, in addition the average length of your menstrual cycle.

Please select the first day of your last menstrual period:

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Usual number of days in your cycle:

A calendar can be used to keep a track of your monthly periods, so this is a good way to know the first and last days. As for the length of your average cycle or period cycle, this would be the time length in days, starting from Day 1 of a menstrual period and ending at Day 1 of the other. A normal menstruation period can take 2 to 7 days.

After entering the required information, the calculator will present the dates in no time without any hassles!

Menstrual Cycle

Most couples have a hard time when trying to conceive naturally, with some taking about one year. If you can relate to this, then you need to take time to understand menstrual cycle as well as the calendar for ovulation as this can improve your chances of conceiving. Knowing your menstrual cycle will help you to ascertain your ovulation days more accurately.

There are three phases in the menstrual cycle: the follicular, ovulation and luteal. The period for ovulation will be your most fertile time and this will occur about 10 to 12 hours after a LH surge. The length of your menstrual cycle is the number of days that the cycle lasts, which is different from the length of your period. The day when your period begins is cycle day; the beginning of a brand-new menstrual cycle.
On average, 28 days is the length for a woman’s menstrual cycle and the period length is 3 to 5 days. However, this is not the case for everyone as some have longer or shorter cycles which can vary monthly by a few days.
To calculate the length of your menstrual cycle, you can count the days from the first day of your period and go up to the day prior to the start of your next period. In turn, the average cycle length can be calculated by adding the length for each individual cycle and then divide by the overall number of cycles.


Ovulation occurs whenever the ovary releases a mature egg into your fallopian tube in preparation for fertilization. If you have been trying to conceive without success, then it is very important to understand your ovulation and menstrual cycle. Knowing this will help you to predict your most fertile days. An ovulation calendar is a proficient tool that can help you to ascertain your ovulating days.

With the help of an ovulation calendar, you can calculate the days when conception is most likely to occur. This calendar can be supported by an ovulation kit as it offers a great way for you to double check the high fertility days.
The ovulation calendar calculates the odds of conceiving by using a method that is based on the ovulation period as well as other factors such as the life expectancy of the egg and sperm. It will provide information that is even more accurate if you know the length of your menstrual cycle. A simple way to determine this is to track the number of days in your cycle, for around 3 to 4 months. You could have the regular 28 day cycle like most women, or it can vary between 29 and 32 days.

Calculating Due Date

When you get pregnant, you might be anxious to know your due date, just like every other expecting mom. In this case, a due date calculator will come in really handy. This tool will use the first day of the last period in order to calculate when you will give birth. It also uses the estimated time for your ovulation to determine when your baby will be born.

All you have to do is type in the exact date for the first day of the last menstrual cycle and the amount of days that your cycle normally runs. After that, you will receive an approximate date for the time when you will give birth. Note that the calculator will only give an approximate date based on the forty week calendar that is used for normal pregnancies. Furthermore, the result will be based on any data that you give. The predictions from these calculators are 80% accurate, so this is something that you need to keep mind. Of course, the real due date will still be dependent on the time when your baby is well good and ready to be born.

364 thoughts on “How to Use Period Calculator

  1. Best

    Please help me to calculate my menstrual cycle. In April I saw my period on the 18 and June on the 16. Please, how many days is my menstrual cycle?

    1. Steffy

      You would also need to provide the date for the month of May. An accurate response cannot be provided without this information.

  2. favour

    Please, I had my menstrual flow on the 13th of June and it finished on the 16th, had unprotected sex with my boyfriend on the 1st of July. Please will I be pregnant?

  3. Cass

    I had my period June fifth to June eleventh, it’s going on the thirteenth of July and no blood whatsoever. If I am correct my cycle is thirty days. I have had sex almost every other day with my partner honestly. Am I late?

  4. dama

    I have difficulties getting pregnant because I don’t know my ovulation date. The details for 2015 are:
    Jan 19
    Feb 15
    March 15
    April 11
    May 9
    June 6
    July 3
    I have a cycle of 27 to 28 days. It lasts for 4 to 5 days. Please I need good answers.

  5. rosewell

    I don’t know my free date. my last date was 10th august and this month is 6th September. I don’t want to conceive now. thanks

    1. Jane Post author

      Hi Rosewell! you have to use some kind of birth control protection if you don’t want to conceive

  6. Amantle

    I had my last period on April 30th 2015 until now but there is no sign of pregnancy

  7. Sharon

    My period is not accurate I the dates…. In the month of August I saw it on the 18 now this month I saw it on the 12…. Please I want to know the cause and how can my period regulate?

  8. fashion police

    I saw my period on the 16th of September and it ended on the 19 of September, when am I suppose to get pregnant?

  9. TTC

    my number of days in my cycle seem to change each month. July 31, Aug, 26, Sept 19. How am I suppose to pin point ovulation if each month the number of days in my cycle is different. the ovulation calculator tells me i have an average of 25 days in each cycle. and that my fertile window for Sept was Sept 26-Oct 1. I had sex on Sept 24, Sept 26, Sept 27, Sept 28, Sept 30, Oct 1, Oct 4, Oct 5. what are my changes of conceiving this month. been trying for 3 months with no luck :(

  10. Lilian okolie

    I saw my last date on 30 october, so I don’t know the time of my free period


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