July 29, 2023

How to Use a Period Calculator

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.


When did your last period start?


How many days did it last?


How long is your cycle?


Here are the results based on the information you provided.

Your next menstrual period is expected to start on

Your next most fertile period is from to

If you conceive within this timeframe, your estimated due date will be

Previous 2 MonthsNext 2 Months

  • Pre-Period
  • Period Days
  • Post-Period
  • Peak Ovulation

Please note that this is only an estimation of your menstrual 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.

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510 thoughts on “How to Use a Period Calculator

  1. my period has just started, I had my period on 14 July which lasted for 7 days. Please how many days cycle is my period? Thanks

  2. Please I had my menses 12 August and for 5days….but woke up this morning bleeding again..does is mean I am having my menses twice? My name is Naa.

    1. Hi there Naa, this indicates that you are having irregular periods. This can be due to change in diet, stress or hormonal fluctuations, etc.

  3. I’ve never noticed any mucus when its my ovulation, I only feel pains around my waist, does it mean ovulation or what?

    1. Hello Ifenowo, there might not be any noticeable mucus, every female experiences this differently, some spot, cramp or have a discharge.

  4. Hi my name is Halimath,I did family planing the injection and have stopped it since June,but I was unable to conceive since,please what do I do to become pregnant fast please because my home is on fire.

    1. Hello Ogunseye bola, you have to keep trying around the time you are fertile. Some women have to try up until a year. If until after a year you haven’t conceived then see your doctor.

      1. Hi
        I also did family planning injection to be precised but I stopped when I wanted to get pregnant again and in two months I got pregnant.
        Please take folic acid too. Thanks

  5. Just checked and I guess the calculation is wrong. Why did I see my period today i,e 29th December instead of 3rd Jan 2018? Somebody please answer me. Thanks.

  6. Please ma when should my next period start and how do I calculate, November period starts 23 and ends 29 of Nov. Then what do I do in an abnormal period. Thanks ma. Aderonke.

  7. What could delay my period? It ended last on 14/2/2018, I had sex on 2/03/2018. I do have a 26 days cycle. Today is 12/03/2016, yet I have not seen it. Am scared am pregnant.

    1. Hello Blessing, well you might be pregnant. Take a pregnancy test 7 days after your missed period to accurately determine this.

  8. Please I have been trying to conceive for more than seven years now to no avail
    Please what could have been the problem

  9. I had an abortion on 9/4/2018. Also had unprotected sex on 14th and 15th but I used post pill afterwards. Started noticing tiny drops of blood on 16th. What could be wrong with me please?

  10. I had sex a day b4 my ovulation several times like that but by there was no sign of pregnancy why?

  11. Hello. I had an medical abortion using mifeprestone and cytotec on d 1St of may, I was 3 weeks pregnant, 2 hours later, I started bleeding heavily with few clots and it stopped on the 9th of may, my breast went to normal, it wasn’t painful anymore, that was d only physical symptom I had. On 10th, I had protected sex, we used a condom. yesterday, I felt slight cramps and saw I was bleeding, it got heavy overnight and it’s been fluctuating. Please could it be that I’m on my next period or I’m ovulating or I’m still bleeding from the abortion or implantation bleeding. I’m confused please.

    1. Hello Nicole, this is highly likely associated with bleeding from your abortion.

  12. Am trying to conceive since six years ago, And my period didn’t flow very well, and it’s not regular, what should I do?

    1. Hello Oludare, see your doctor for a physical assessment as to why this might be happening to you.

  13. I had my period on the 4 August 2018 and it came again on the 29th of August when am I suppose to HV my period am worried.please help

    1. Hi there Onyeforo, you did not provide sufficient details. Some women have 2 periods in 1 month for varying reason though it is not normal.

  14. Hi
    Am married for eleven months now trying to get pregnant but up til now, secondly I use to see my period every after 24 OR 25 days and I bleed for like 3 to 4 days when will be my ovulation day exactly? Because my husband is staying with me I do visit him and he do same

  15. Charting is much better than using an some online ovulation calculator. Those predictors don’t know your body – you do. Every woman’s body is different, and calculators don’t take that into consideration. I used one to calculate last month’s ovulation…it was 3 days off. This month…4 days off. So…

  16. Pls complain for me . I saw my menstruation on the 14 of July and should see it on the 11 of august but now am seeing it on the 8 which is yesterday, am really confused what will I do

    1. well that’s just two days earlier. it could be caused by stress or some other factors. I wouldn’t be too concerned. is your period usually very regular?

  17. Hello , am still confused on my menses I saw it on the 14 of July and august on the 8 pls tell me what happened and again I don’t use to see my ovulation I can only notice discharge of whites , watery ,and no odour in it. Thanks

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