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





Hi, I have always had very irregular period so it’s very difficult to calculate when I ovulate. My first day of period was 08 Jun, then 11 July and then 17 August. It’s 25 Sep today and I have seen my period. I tested negative. I need help please.
Do you mean to say that you haven’t seen you period? Have you had a period by now? You can wait another week and take another test. If it is still negative then you need to consult your doctor to determine the possible reasons for you period being delayed.
Hi my name is Maureen I was having fun with my boyfriend but we didn’t have sex, his sperm touched the outside of my vagina. Is there any chance that I’m pregnant? I’m a virgin and one of my breast nipple hurts.
The chance of you becoming pregnant by this action is low. Can you identify why your nipple hurts? It is is possible that it was bruised when you were both “having fun”.
I had my period August 7 to 9 and have sex at August 25 and got my period on the next day August 26. Is it possible that I’m pregnant?
Hello. Knowing the number of days in your cycle would help to answer your question. This information is needed to provide you with an answer.
Hi, I saw my period on the 9th of July 2015 and ended on the 11th of July, I had sex with a guy on the 12th of July and he came inside of me, I had sex with my bf on the 13, 14, 16, 17, 18, 20, 22, 23, 24, 25 of July and he came inside of me also. Now I am pregnant, who could be responsible for the pregnancy? Pls urgent reply needed. Thanks.
What is the usual number of days in your cycle? This is necessary to confirm the days that you were fertile.
Hi steffy, thanks for your response, since april when I saw my period twice, which was on the 5th and 19th of april, which lasted 3days each time they came, then I saw my period on the 25th of may through 28th of may, I never saw my period the whole of june, although have been having unprotected sex with my bf and have been on pills for preventing the pregnancy, I did a blood test since I didn’t see my period in june, it came out negative, few days later I saw my period on the 9th of July, which lasted for 3days as stated on the first message sent to you…have not been regular since I saw my period twice in April. I need to know who is the father. I hope to read again from you.
Hi. I had my first period on September 3 and I had sex on September 11. Can I ask is this safe or am I pregnant. Hope you reply soon.
Hello. The best way to assist you is by knowing how many days are in your cycle. If you have a 28 days cycle, you would have been most fertile on September 15 to 19.
Had my last period on August 24th, and the period tracker said I was suppose to start yesterday. I have had unprotected sex 5 times since my last period, not on any birth control anymore. My periods are 5 days long and I am confused. I usually start on the 24th, so why is it saying I am late?
Hi. Your period may be late for many reasons including those listed at our link http://womanjunction.com/missed-menstrual-cycle/ . If you have unprotected sex especially during your fertile days then the risk of becoming pregnant increases. If your period is still late then you can take a pregnancy test for confirmation.
My last period was August 15th. I had intercourse on 08/23, 08/26, 08/30, 09/02. I was supposed get my next period on September 12th. I took a pregnancy test September 21 + positive.
Hello.
my last period was on August 25th, 2015 and I had unprotected sex with my husband on September 19th, is there any chance that I am pregnant? 🙂
Are you seeing any symptoms of pregnancy ? such as sore boobs , and so on ?
Paty that is similar to my case. My last period wad on 23 September. I had sex after then. My next period supposed to be on 20th September, am I pregnant. I have done the test it is negative.
My last period was the 18 Aug 2015 made love and had my period after that on scheduled time but only three days. Now my next cycle should be 15 Sep 2015 but no sign of period can i be pregnant after I had my period last month?
Hello. It seems you have a 23 days cycle based on the information provided. This means you were most fertile on August 25 to August 29. If you had unprotected sex during this time then the chance of being pregnant is high. If you did not have sex during this time then you period may be late for other reasons including stress and fatigue.
I started my period on August24/27,I had sex on d 29&30 of d same month and also have sex on d 6&7 of sept ,have a 28days menstral cycle and my next period should be on d 21st of sept ,just want to know what is d possibility of me getting pregnant cos today is 21 and still expecting my Period but have not seen any sign
Hey I had my period August 21-24 and had sex sep,3-6 and I’m 4 weeks pregnant ☺️ Take a test I took one on the 15th and it was an opposite result.
goodmorning
please need help. my last cycle for august was on the 21st till 23rd , this month it should have started on the 18 september but till today i haven’t seen my periods. i had sex several times with my husband. i’d like to know if it is possible that I am pregnant or my period is just delaying. and when is the right time to do a pregnancy test or is still early to test.
Hi Chammy, you can take a test as soon as you miss your period if its negative you can still be pregnant so it would be best to check with your doctor.
Hello I also had my period the 21,23 and had sex sept 3,4,5 and received a positive pregnancy test on sept.15. So you should take a pregnancy test ASAP if u had sex sep,3,4,5 it was when we ovulated.
Hi my last menstrual was July 28, 2015 and I took a test Sept 2nd it was negative but today is Sept 20th and I still have no period….im confused.
Hello Paris, You can still be pregnant even with a negative pregnancy test i suggest you take another or visit your doctor to be sure.
28 day cycle last period was August 17 it is now September 21 no period and neg test. Yes had UPS around the big O and have had small bleeding ( wiping after bathroom, just on tissue) on 3,4,5 days past expected period. I’m normally like clock work, and no signs of pregnancy other than missed period but tomorrow marks a week last.
Hi, my name is brittany my menstrual started on August 16-August 20 me and my boyfriend had unprotected sex the day after it went off my menstrual was suppose to start again September 13 and here it is the 20th of September and it still isn’t on i took a home pregnancy test on the 15th and it was negative could i still be pregnant?
Hi Brittany,yes you can still be pregnant with a negative pregnancy test take one more or visit your doctor.
What should I do to conceive fast, I want to get pregnant ths month
Hi I had my period August 14-18, and now it September 20th 2015 I still haven’t seen it yet. Could it be I might be pregnant ? Having taken any pregnancy test yet. I’m confused
Hi. there’s always a possibility if you had unprotected sex in the meantime. please read our FAQ page