You want to know the dates of your next period, ovulation or due date? You came to the right place. If you’re in a hurry you can go straight to our menstrual cycle calculator (click here) or Infographic with key information about calculating your period (click here).
Check the full table of content below.
Table of Contents
- Introduction
- Period & Ovulation Calculator
- How Do Menstrual Cycle Calculators Work?
- Using a Period Calculator
- How To Calculate Your Next Period & Ovulation Infographic
- Understanding the Menstrual Cycle Properly
- Understanding Your Next Menstrual Cycle and Fertilization.
- Some Important Information Regarding the Calculator
- Learn more
- Frequently Asked Questions
Introduction
If you want to stand the best chance of getting pregnant, then you need to know when you are ovulating. This is the time of the month when women are in their most fertile period. Ovulation usually happens around day 14 of the cycle [1]), while there is a greater chance of a sperm reaching the egg and fertilizing it.
However, one of the biggest problems and question that people have is knowing how to calculate their next ovulation date and when is the best time to aim for intercourse. This is where technology can come in handy. You can use an ovulation calculator, like the one below, to get a rough estimate of when you are going to ovulate next.
Ovulation & Period Calculator
Use this period calculator to calculate your next period (menstruation), fertile period, ovulation, and due date. To give you an estimate as to when those time frames are, please provide the requested information and press the Calculate button (results will be shown below, together with a fertility calendar):
When did your last period start?
How many days did it last?
How long is your cycle?
Below 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
- Pre-Period
- Period Days
- Post-Period
- Peak Ovulation
Please note that this is only an estimation of your menstrual cycle
A period calculator is not the same as talking to a healthcare professional, so this is just to aid you in coming up with the most accurate calculation possible, on your own.
Also, keep in mind that these calculators will be useful to women with a fairly regular menstrual cycle. For women with irregular menstrual cycle tracking other ovulation symptoms or using an ovulation predictor kit might give more accurate results, all of which we’ll cover later one.
How Do Menstrual Cycle Calculators Work?
Menstrual Cycle Calculators vary in complexity. Some will ask you for information such as your average body temperature, as well as various other bits and pieces about what your body is currently going through.
While there are women who measure their basal body temperature, it’s not something that the everyday woman uses.
However, it is a rather accurate way (when done 100% correctly) to determine when a woman is ovulating.
Some feel that these types of cycle calculators are “overkill”, but for those who are using the basal body temperature to prevent and plan a pregnancy, they have this information handy.
If you aren’t into this type of strict monitoring, a simple calculator like the one provided here can give you really good results and help you plan.
Using a Period Calculator
The first thing that the period calculator will ask you is the date of your last period. With so many apps available now, this should be information that is readily available.
And just remember, when calculating your period, you use the first day of your last period. This was the beginning of your cycle.
If you don’t know the exact first day, calculate back from the last day however long it lasted, and start tracking now. Especially if you are trying to get pregnant.
Some will use a menstruation calculator to figure out when to expect their periods and when to expect PMS. PMS is due to the change in hormones that cause periods and pregnancy.
When you are pregnant or during your period, these emotional and physical symptoms subside [2]. Some women can then plan to change their diet a few days before they expect PMS and help to alleviate some of the symptoms.
The next piece of information that you will be asked for is the average length of time between your periods. This is the length of the menstrual cycle. Of course, the human body does vary wildly here, and whilst some months there could be 30 days between your period, others it could be as low as 25.
However, you are only after an average here. Being as accurate as possible is important as this will affect the results that you are given which can have a profound effect on when the calculator tells you is the ideal time to try for a child.
Finally, you will be given your results. Based on the information you provided, it will calculate when your next period is anticipated and also your fertile period which is when you stand the best chance to get pregnant.
How To Calculate Your Next Period & Ovulation Infographic
Understanding the Menstrual Cycle Properly
While you may already have a fair understanding of your own menstrual cycle, there are women who have cycle lengths that vary. Sometimes, your own cycle can be as short as 23 days on cycle and 28 or 30 days the next.
When a variation in menstrual cycle length occurs, it usually happens before you ovulate. This is referred to as the follicular phase which encompasses menstruation as well and ends when you ovulate [3]. A woman generally ovulates between days 12-16 of their cycle which is the start of the luteal phase [4].
There is a multitude of reasons as to why your period could be altered, be it stress or medications, even weight gain/loss or travel. Unless you think you are pregnant, it could be a myriad of reasons that have your period coming irregularly.
Understanding Your Next Menstrual Cycle and Fertilization
If you are trying to get pregnant you need to understand how the menstrual cycle works. The process starts when the thick lining of your womb starts to break up due to the decrease in estrogen and progesterone levels.
Without a sufficient amount of these hormones, your body will shed the lining and it will start to prepare for your next menstrual cycle.
However, if a sperm does make contact with and fertilizes the egg, it will close all pores to prevent more sperms from getting in there. The fertilized egg will stay in the fallopian tube for 3-4 days and then move to the uterus and attach to its wall, staying there for the long haul of pregnancy.
Your body will produce human Chorionic Gonadotrophin (hCG) or pregnancy hormone right away (which can be seen within 6-8 days by a blood test and can take about 2 weeks if not longer to be seen in urine tests) [5].
The body will continue to produce the required estrogen and progesterone hormones so that the womb lining will not be shed and the placenta can grow mature enough that it can support the pregnancy.
Some Important Information Regarding the Calculator
The period calculator above also comes with a fertility calendar. You can navigate through different months by clicking on the NEXT 2 MONTHS and PREVIOUS 2 MONTHS links. This allows you to plan and prepare for your fertile and menstrual periods in the upcoming months.
What you do need to remember though is that the information isn’t 100% accurate as it is impossible to predict the human body.
Your fertile period gives you a good range in when to have intercourse to potentially get pregnant. You can learn more about the likelihood of conception in this article.
That being said, the menstrual calculator is still an extremely useful tool. It provides a simple way of knowing when to anticipate your next period and when is the best time to try for getting pregnant.
This could be a huge help for those with busy schedules to plan their days to start their family.
Learn more
Want to learn more about your menstrual cycle? Find out how does the Fertility Calculator work or how to to calculate your period manually.
Want to know if you’re pregnant? Take this online pregnancy test, read more about the most common reasons why your period might be late or find out when it’s the best time to take a home pregnancy test.
FAQs
How do I calculate the length of my cycle?
Can I have sex during my period?
What is the average length for periods?
My period is really heavy; what can I do to change that?
Can I get pregnant if my periods are irregular?
How do I know if I need to see a doctor because my heavy periods?
Can I prevent PMS?
Do you have any other question about your period, ovulation, pregnancy or other related topics? Check out our Frequently Asked Questions page.
References
- Your Fertility. Women’s Guide to Getting the Timing Right [link]
- Mayo Clinic. Premenstrual Syndrome (PMS). [link]
- Better Health Channel. Menstrual Cycle. [link]
- see above #3
- WebMD. Pregnancy and Conception. [link]
- Eleanor Jones via Cosmopolitan. 10 Questions Period All Guys Want Answered [link]
- Playtex. Period 101. [link]
- The University of Iowa. Birth Control Pill Fact Sheet. [link]
- WebMD. Slideshow: Answers to Your Top period Questions. [link]
- see above #9





I had sex on March 3rd or 4th with someone and started my period on March 10th. Had sex with a different person from March 10th through the end of March. Neither of these guys wore protection, but the one from the 10th-end of mArch was cumming in me definitely. I took a pregnancy test at the doctor on April 1st and it was negative. I had sex with a different guy on April 5th. I took a test on April 6th or the 7th and it was positive. My due date is December the 17th. I’m so confused on who the father is :(( pls help me
Hi ,
it is quite simple, a pregnancy test need 14 days to trigger. doing a test 48h after having an intercourse is completely useless… from your positive test go back 14 days and think with who you had unprotected sex. And please let me tell you that, unprotected sex with numerous partners is not making you at risk to have unwanted pregnancy but expose you also to many sexual transmited deseases that can also affect your unborn child.
Hi
I had my period sept 14-18th. I haven’t had a period since. It was due October 6th. I’ve seen light spotting only when I wipe which that just started a few days ago and it’s only periodic. I decided to take a test last night and it was negative. However I’m feeling fatigue all the time. Anyone experiencing thus? If so, we’re you pregnant? Any advice would be appreciated. Best wishes to you all that’s ttc! Please wish me luck. Me and my husband are trying to have our first 🙂
Hi , from the dates provided you have a short or irregular cycle. The best way to make sure you test yourself at the good time and have an accurate result is to test yourself, with the first morning urine and to wait 14 days after your last unprotected intercourse. If it is still negative, dont be sad .. for next cycle try to have sex one day on 2 during your fertile window it will allow more mature spermatozoids to be launched and increase your chances to conceive
Good luck
I had unprotected sex on the day am supposed to start my period(18th october) is it possible I will get pregnant.
Hi there, I had unprotected sex on the August 29th which is the ovulation day but my boyfriend didn’t cum inside me nor release any sperms. He just tried putting into me for few seconds and I think there is a little transparent pre cum. My period came on the september 14th which is on time and lasted for 5 days. My next period should be on the October 11th but it still haven’t come until now. What could be happening?
Hi,
skipping a cycle can happen.. if you are uncomfortable with this situation, have a chat with your physician that can provide you with more technical answers.
Good luck
There is what we called menstrual variation so maybe it varies that is why you’ve not seen your period and after changing you will start counting again from the day you will see your period
I had my period Oct 1 2014 it end on the 5th of oct. I had sex on Oct 11 and 12. My boyfriend did release inside of me and he went deep, could I be pregnant?
Yes… you may!
my last menstrual cycle started on 6 sep and i have irregular periods sometimes it comes in 2 months or sometimes in 35- 40 days and i had sex on 22 sep can i be pregnant..
Hi,
where there is unprotected sex, there is always a risk to be pregnant. Risk are minimal but existing. Many factors have to align himself to . To avoid unnecessary stress as you have an irregular cycle to you test yourself with a pee on the stick test 14 days after the not protected sex, it is the time required to built enough HCG hormones in your body to trigger the test. Use the first morning urine as this one is the most concentrated in HCG
Good luck
How many day of being late should you take a pregnancy test?
Hi , some test are sensitive enough to trigger a positive 2 days prior your due date. Most of the the day you are due. I recommend you to wait to be late 2 days before testing yourself as you could trigger a false negative in case you conceive at the end of your fertility window
Good luck
Pls i need to know if i can get pregnant because i had an unprotected sex 3days out of my 5days ovulation periods but my bf did not release in me
I am 42 and I had my last period on august 27 and it lasted until September 5. I did not have a period in September. My prior july period was on the 13th and lasted until the 18th of that month. What can be going on?
Hi , having one weird cycle is normal, we have changes in our lives, so the cycle too ! If it keeps being irregular and random don’t hesitate to speak about it with your physician, he/she will investigate the reason and propose you solutions.
Good luck !
My circle is 28 days but this month I got my period on 1st of October it was supposed to come on 28th of September so my problem is when am I ovulating this month,,,am TTC
Hi , your ovulation will occur between the day 10 to 14 of your cycle, the day one being the first day of your period. You can always track it more precisely by taking your temperature every morning before getting out of bed and add it to your calendar, you will see the temperature will increase starting 2 days before the most fertile day
Good luck !
Hi, 21 years old and I had sex on October 9 and my period start on September 20 so I want to know if I’m pregnant.
Hi. The answer depends on the number of days in your menstrual cycle. For instance, if you have a regular 28 days cycle, your next menstrual period would be expected to start on October 18, 2015 and you were most fertile from October 02 to 06, 2015.
I check the menstrual Calculator, my first day of my last period Is on 1 sep 2014, the calculator shows that I will get on the 29 sep 14. but till now I still haven got my period
Ok so my last period was either Aug 29,30 or 31 I’m really not sure, now my guy and i had unprotected sex on the 4,9 and 16 of Sept and each time he ejaculated inside of me. Now from the menstrual calculators I’ve been using it says my period should have started Sep 26 but it hasn’t, could i be pregnant?
I totally understand you. I’m in the same situation. I can’t remember the exact day when my menstrual period started. I had unprotected sex on Sep. 13 and on the 19th. Not sure if pregnant or if my period is late.
Hi. My period came two times in the month on august 2 then the 29 .now september is coming to an end and I haven’t got my period yet is something wrong with me?
my period started 14 September and lasted till 18 th. just got married and I would want to know the probability of getting pregnant this month. thanks
I had my period sep. 23,2014 and I had unprotected sex sep. 24,2014 could I be pregnant
my Dr said i should ovulate end Sep first of oct… but then said try to get pregnant end of oct first of Nov..did she mean i may know something by then … i have been trying an my last period ended Sep 19 so just trying to get answers an not stress about it bc i know stress throws everything off