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





My boyfriend and I have been trying to concieve for a year as of Christmas Eve this year. We have had no luck what so ever. According to this calculator, I was supposed to start my period on the 10th of december and it hasn’t come yet (today is the 19th). I took pregnancy test and it was negative. My period is never regular so I never know when I’m ovulating. So we have unprotected sex every day that I’m not on my period and we still have no luck. What should I do?
Hi Emily. This guide includes some helpful tips on how to get pregnant. good luck
My periods was on 27th Nov 2015 and i had sex with my patner on 16th & 17th december will i get pregnant or not… pls suggest me how to avoid the pregnancy
Hello, If you had unprotected sex its possible to become pregnant,you can avoid a pregnancy by taking a after morning pill but it is only effective up to 72 hrs.
Hi I had a D&C on 2/11/2012 and my flow started on 9/11/2012 and then i had a second flow on 21/11/2012 though after the first flow I had unprotected sex and took contraceptive my cycle is usually 28 days. please I’ll like to know my next period and ovulation days as am yet to see anything. Thanks!
Hello, Your next menstrual period is expected to start on December 19, 2015, and You next most fertile period is December 03, 2015 to December 07, 2015.
Hi I’m 20 Years old I am trying 2 get pregnant I always start my period around the 17 and my cycle lasts about 5 days so when will I ovulate?
Hi my last period was on Nov 11 it lasted for 3 days. i had unprotected sex November 25-29…..On December 10 my period came and lasted 1 1\2 days. is there a chance that i might be pregnant??
Hi, If that was actually your period and not some other form of bleeding associated with pregnancy you are not pregnant because you cannot be pregnant if you saw your period.
Please,i had my menses on the 8th of December and ended on 12th December. I had unprotected sex on the 18th of December,Can i get pregnant?
Hi, Yes you stand a chance of becoming pregnant whenever you have unprotected sex.
Hi jane, I am in the same boat. Period on december 23-25, 2015. BF ejaculated three times on period on Christmas day and stopped immediately the next morning December 26, 2015. Period calendar states ovulation from December 26, 2015 to January 1, 2016. What should I do now. Have no period just a slight light brown stain. Help
Hi, I had my last period in December 5 and made love with my BF december 9. And he ejaculated inside me. My normal cycle is 28 days but this time my cycle was 23. (Previous mens was November 12) what are the chances of me getting pregnant? I am not ready yet. Thank you and I hope a quick response.
Hi, Once you have unprotected sex you stand a chance of getting pregnant,wait a week or 2 and take a pregnancy test.
Hello , I’m seeking advise. I recently had unprotected sex on the 10th of dec today is the 17th I usually have my periods on the 22-25th . I’m a little scared because he came inside me more than once. Eventhough my period hasn’t started yet could there be a chance that I could get pregnant?
Your chances of being pregnant depend on whether you were fertile on or around the date that you had sex. Can you confirm the number of days in your menstrual cycle and the first day of your last ? This information is needed to provide you with the most accurate response.
Hi. My gf and I had unprotected sex on 15 Dec. Her period was Nov 20. But we opted for an after pill because we ain’t ready to sire kids. When should she expect her next period!? Is there a possibility of conception even after using after pill? Please advise.
The date of her next period would be dependent on the number of days in her cycle and the first day of her last period. This information was not provided so we cannot tell. Yes it is possible to conceive again after an abortion.
I saw my period on 4/12/2015 and my cycle is 28 days. When will my ovulation occur and my next period? Please, I need your reply urgent. thanks
Your ovulation dates are December 24 to 28, 2015. The next period is due on January 9.
I had unprotected sex on the 5th of December and my due date is the 21:St I took the pill ???? the next day on the 6th. Will I come on now or on my due date?? Help anyone.
The morning after pill may cause a disruption in your menstrual cycle. This means your period may come before a after your due date.It’s jus a matter of wait and see.
My previous period is 11November BT at this month I not get my period 36day go what is the reason I never do sex BT I am afraid why my period is not coming plz reply me fast
A friend had her menses on 25th October and had sex on 13th November. She took Postinor2 on that same day and her menses came on 18th of November instead of 25th November but her menses is not in its one day late and the pregnancy test is still negative…Is she pregnant? What might be the cause?
It is possible that she’s not pregnant. The Postinor 2 is very effective if it is taken immediately after sex. Her period may be late if she’s stressed or experiencing an emotional situation. We’ve compiled a list of eight things that may be affecting her cycle…read more here http://womanjunction.com/8-mess-period/
Hi my name is Cassie and I’m curious I’m now 29 weeks pregnant and going by my sonogram there stating the first day of my last period was May 26th 2015 but I didn’t bleed till the 29th of May. I had protected intercourse on May 27th and protected intercourse June 5th. I’m sure one of the intercourse wasn’t so protected but I’m curious what day would most likely be the time I got pregnant?? There stating June 8th was the day I conceived and my due date is Feb 29th 2016 I need answers
Hi, Well its hard to be exactly sure the exact time you conceived , what the doctors did was give you a estimated time they think you could have gotten pregnant.
Hi my name rachel i had unprotected sex on the 8th and i started ovulating on the 12 and i had unprotected sex on the 14th could i be pregnant
yes, you could as you had unprotected sex during your fertile window
Hi My Last Period Was On Sept 28. I Have A Boyfriend That I Been Dating For A Year We Don’t Use Protection, But On Oct 11 Me & My Kids Father Had Unprotected Sex. I Find Out I Was Pregnant On Oct 31 , I Conceived On Oct 12 I’m Just Confuse Who The Father. I Need an Answer.
Hi, The only way to completely be sure who the father is by doing a DNA test.