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





Good morning. I had my last period on April 29th. It lasted the regular 5 days and on the 10th of May I had sex which was my ovulation day and on the 14th again. My period should have came on the 24th of May and it is not here. I’m now 5 days late, am I pregnant?
I took early morning pills and since then my last 2 menstrual period came 16 and 17 days apart. My last period came on the 12th of may… Now I had unprotected sex just a week before my next period (assuming my cycle has gone back to 24 days). He didn’t cum inside me but I am scared of pre-cum,
what are the chances of me being pregnant?
Hi, I am trying for my 2nd child and looking for some advice and maybe help to work out dates.
I come off my pill on the 22nd of February.
Had my 1st period on the 24th of March.
2nd period on 26th of April.
I have not had another one and took a test last night and it was negative 🙁 …
I started my last period on April 28th and now for this month of May I haven’t gotten my period. Today is the 27th and I am cramping a little and I did realize I had a little brown discharge. My last period before April was on March 31 and usually my period last 4-5 days. Can I possibly be pregnant or is my period just late?
In March i got my period on the 31st to 6th of April, then i had my lmp on 23 april. This month i got my period on the 20th of May and it ends on 25 May, please help me when should i ovulate and get pregnant? I need fast answer.
Hi Emmah. It sounds like your cycle is a bit shorter than average (roughly 25 days). Based on that calculation, you’re likely to be most fertile from Thursday, May 28, 2015 to Tuesday, June 2, 2015.
I had unprotected sex on April 30th, my last period from the first date was on/around April 18, 2015. I haven’t gotten my period since and my period is usually regular it’s the same every month. I get it the third week of every month, I am now 6 days late. I am only 16. I am fully prepared mentally but of course not physically.
Hi Amanda. If your cycle is 28 days, it looks like your most fertile days were from April 30-May 4. So chances Are you may be pregnant. Best wishes.
I had my last period on May 10, my period came on my birthday may 6 i’m 18.. and to be honest i do honestly wanna be pregnant. I was once before but it didn’t work out so i’m trying again.. and i just can’t seem to get pregnant.
You should not worry about it to much and constantly think about wanting to get pregnant, sometimes your body want to do the opposite also, ask your doctor maybe it’s also your partner. My uncles girlfriend had to get a shot because something about my uncles blood didn’t go with his girlfriend. I wasn’t to sure but check with your doctor hope you get what you want ( :
Hey . I Had My Last Period April 8 And It Lasted Until April 13 . My Period Suppose To Have Came On May 8 or 9 But It Didn’t. On April 20 I Had unprotected sex but I took a pregnancy test May 9 & it was negative . Now I’m confused BC I had unprotected sex again and my boyfriend came inside of me May 17 ,2015 & I started cramping very badly a day after . And now I’m bleeding and its differently my period. Can anyone tell me if I can still get pregnant while my period is on BC it was almost two weeks late and the day I had unprotected sex ( may 17 2015 ) it came on two days later .
You can still get pregnant while on your period. You should probably take another pregnancy test or just go to planned parenthood to get checked out. Also if you know you’re going to be having unprotected sex, use Birth control Pills/condoms. Buy some Planned B next time if you have unprotected sex. Good luck!
You are able to get pregnant at any time during your cycle but it’s just less likely to happen on certain days including the days of your period. Your period could’ve been late for several reasons outside of pregnancy including stress, changes in your weight, birth control pills, medical conditions etc. You may or may not be pregnant because it may have been too soon to get an accurate result and sometimes implantation bleeding can be mistaken for a period. If your flow is heavy enough then you may be in the clear but to be sure I would suggest you see your doctor for confirmation and notify him/her of how late your period was.
Hi. My last period was April 17 lasted 4 days. It is now may 20th and still no period. I ovulated on the 1st. I have all the pregnancy symptoms but hpt was negative. We are ttc. Could I be pregnant?
Hi Amy. Yes, you could still very well be pregnant. You might get a false negative test result if you take a home pregnancy test very soon after you think you may have conceived, or if you don’t follow the test instructions correctly. A home pregnancy test will be positive only if it detects the pregnancy hormone human chorionic gonadotropin (hCG). When an egg is fertilized after you ovulate, it takes about a week to travel through a fallopian tube to the uterus. And your body starts producing hCG only after a fertilized egg implants in the uterus.
If it’s very early in your pregnancy, your body might not have produced enough hCG yet. In that case, you’d get a negative result at first. Also, some tests are more sensitive than others, and no test is 100 percent accurate. And a few women have such low levels of hCG during pregnancy that home tests can’t measure it.
Although some tests can detect hCG the first day you miss your period, you’ll have a better chance of getting an accurate result if you wait a week. Don’t time the test based on when you think you might have conceived. Sperm can live in the fallopian tubes for up to five days, so it’s possible you could have conceived several days after having sex. If it’s been more than a week and still no sign of a period, you can take another test but still see your doctor regardless of your results to confirm whether or not you’re pregnant because you should’ve had your period by now.
Hi my last period started on April 13 I was suppose to start my period may the 11th I had some cramping and headache but no bleeding tissue was clear haven’t tooken a pregnancy test yet. is it too soon to test
Hi my last menstrual was April 13 it ended on the 17th on that night I had unprotected sex and my period started back for 2days 18th and 19th. Could I be pregnant or should I start counting my cycle from the second time it came on?? Did I miss it or give it more time
Hi there. To calculate your cycle you always count from the first day of your last period so counting from the 13th would’ve been accurate regardless of how long it lasted. It is likely that your period never really ended on the 17th but instead lasted for 6 days. It happens from time to time where you might have a short ‘break’ in your period where you don’t bleed for a few hours and then the next day it seems as if its back so this was likely the case. This could happen for various reasons: your uterus may be in a flexed position, stress might be the cause, your progesterone levels may have changed, etc. Everyone is different so it varies. It may happen just once but if it continues, notify your doctor immediately about these ‘pauses’ during your period. If you’re on a 28-32 day cycle, you would’ve been due for your period between May 11th and 15th which would mean that you are late. Yes it is possible you could’ve gotten pregnant during the time you had unprotected sex on the 17th but it is not likely so the delay could’ve been because of other factors such as stress, changes in weight, your overall health etc. The best thing to do would be to check with your doctor to confirm your status.
Hi, i am trying for baby, my last due was on 27th April, that time,blood flow was not good. we are having sex after 10th day for baby. but on day 17th, my period comes, with heavy blood flow. please suggest and help.
Hi I had my cycle March 27-april 1 then I came on april 21 – April 26 I have the app on my phone and it let’s me know when I’m due for my next cycle and it says may 15 or 16 I’m sorry trying to remember off the top of my head but anyway I haven’t seen it yet and I took a test but it says negative. . I usually come on my cycle around the same time the app say.. help please
Hi Ashley. Based on the dates you’ve provided, it would seem you’re on a 25 day cycle. The app would therefore be correct in estimating a May 16th due date for your next period if 25 days is the average time for your menstrual cycle. If this just happens to be a short cycle for this month and not a usual thing then you may still get your period in the next few days should your cycle be longer on average. If you had unprotected sex and you are pregnant, you may have gotten a false negative due to taking the test too soon but if you didn’t have intercourse and still no period then something else may be an underlying factor for not seeing your period yet. Either way, if you haven’t had your period as yet for the month of May, you should definitely schedule an appointment now to check with your doctor if that is the case.
I went on my period on the 31st of March. I tested 3 times and it was negative. On the 12th of May l started spotting pinkish discharge. my period is normally heavy. Please help. Could l be pregnant? ? I want a baby now same as my husband
Hi, There are a lot of reasons for your cycle to be disturbed, after 3 tests turning negative … i think it is clear that you are not pregnant. Spotting is a natural phenomenon also. If you have any concern or issue to conceive please feel free to have a talk with your physician
Good luck
i had my last period on 30th of march to 1st april. I had unprotected sex on 10th but took emergency pills on 11th. I had unprotected sex from 16th to 18th everyday. my worry is which day did i conceive coz iam 1 month pregnant. on 10th or around 16th. help pliz
congrats honey..
hi uhm…my period was on the 28th of April and according to the period calculator I had unprotected sex 2 days after ovulation…is it possible for me to get pregnant?…I’m worried!
yes you could possibly be pregnant! studies show and say sperm stays in your system down there up to 3 days. best thing to do is take a clearblue or first responce early result test . also go to doctor to do blood work. good luck, hope my advice worked