How To Count Your Period Cycle

Posted on July 4th, by The Period Blog in FAQ, Learn about your body, Period Tips, Tutorials. 86 comments

When I was first taught how to count my menstrual cycle, I was told:

“The first day of your cycle is after your period ends”

And I thought… wait… but sometimes my period is very light for the last couple days and all I have to wear is a pantiliner… does that still count as my “period”? Which day counts as the first?

When girls say “I’m on my period” or “I have my period”, we usually mean that we are bleeding. So when my sex-ed teacher said “The first day of your cycle is after your period ends”, I thought she meant when we stopped bleeding.

I now realize what she meant to say was that the first day of your period is when your period cycle ends and you start to bleed.

I was confused because my sex-ed teacher used the term “bleeding” and “period” and “cycle” interchangeably to mean the same things and to mean different things. Way to confuse a 10 year old!!!  I was in grade five and had no idea what she was talking about.


Okay okay enough story time. So keep reading and I will teach you how to count your period. It is quite simple actually.

You can mark the starts of your period on a calendar or school agenda, make a note in your cellphone, or use an online period trackers:


Or if you have a smartphone, there are even some apps:


An entire period cycle is on average 28 days.

DAY 1-7: The first day of your cycle is the day you start to bleed.

DAY 8-11: Your endometrial lining starts to thicken in preparation for ovulation. Your endometrial lining is basically your period before it’s out of your body.

DAY 11-15: Ovulation occurs and this is just a fancy word for your body releases an egg and plants it into the endometrium lining.

DAY 16-25: Your endometrial lining continues to thicken

DAY 25-28: The endometrial lining starts to shed or in other words detaches from your endometrium, resulting in YOUR PERIOD!! Cycle restarts at DAY 1. (This is of course assuming you do not become pregnant)

When I was taught this I thought, how does your body so accurately know regulate its hormones to bleed exactly every 28 days?

If we were to look at a sample of 100 randomly chosen girls, the average length of their cycles would be 28 days. Your cycle will probably not be exactly 28 days. It may be less or it may be more and this is completely normal.

My cycle used to be around 30 days. Now my period cycle is about 45 days.

If it is your first time getting your period, your period cycle may be irregular. This means that your periods may be early or late. Having your period is a big step in puberty and your body is just not used to this change yet. Your period will become less irregular in 1 – 2 years. (But obviously you know this because you pay attention in sex ed!)

If you are trying to become pregnant or trying to avoid pregnancy, the days inbetween each cycle are very important. Please see your doctor if you have any questions regarding pregnancy and pay attention in sex ed class!! It may be an uncomfortable class but you do not get many of those classes and those are the most important classes of your life and probably one of the few you will remember!

When I first started my period, I never counted the days. I was not sexually active so missing a period wasn’t a concern for me. But there are actually many reasons to start counting your period besides pregnancy.

Reasons to count your period:

  • To get a sense of how long your menstrual cycle is
  • …So you know when you can wear white pants or that really short skirt
  • …So you can match your underwear to your pad or tampon of choice, ie. wear granny panties
  • …To know when to carry pads and tampons
  • …To know when your girl friends have their period (if you hang out around them enough, they will probably also be on the same cycle!)

Well I hope this post was helpful and I truly hope that sharing my own personal experiences will make you feel more comfortable to talk about your period even if it is talking about it with your mom or your doctor. I tried to make it as simple as possible so hopefully it was easy to understand for all the girls who just started their periods.

How do you track your period? Please share in the comments below!

The Period Blog does not provide medical advice, professional diagnosis, or treatment. Please check with your doctor regarding your personal health care decisions, and seek immediate care in emergencies. The Period Blog is not a substitute for medical or other professional care. If you are experiencing any problems with your period, please DO see your doctor! After all, it IS your uterus and you only get one.

86 thoughts on “How To Count Your Period Cycle

  1. I’ve always wondered how girls are able to set each other’s cycles’ off. How often and close do people have to be to each other for that to happen? A post on this would really be interesting!

    • The periods coming about the same time dates back to the prehistoric times when we lived as tribes and much like animal instinct we had breeding times. All the women of the tribe would become fertile much like animals in a herd now. Picture lambing in the winter or calfing in the spring. :)

  2. Hey! I just have like two questions about my cycle. Okay so I got my first period last october. I’ve had very normal periods that started and ended on the same day until two months ago. Two months ago I was like 6 days late and last month I didnt have it at all! Im not sexually active so I know I’m not pregnant. The only thing I can think of is I started a diet last month and I’ve been under a lot of stress lately. Do either of these things change your cycle? Also before my period I gain like 8 pounds of water weight. Is that normal?
    Thank you!
    oh p.s. i dont know if this helps but Im 14 yrs old.

    • Hello! I’ll jump in on this one. When you first start your period it can be wacky. Some women will have a perfectly regular period right away but when I first started it was never predictable. So having it be 6 days late is totally normal it can take a couple of years for it to figure itself out.

      As for it not being there at all – again totally normal. If you make a major change in your life or are really stressed out your body will decide not to ovulate that month (it thinks hey – not a good time to have a baby) and so you don’t release an egg, the body doesn’t have to prepare for the egg, so alas, no period. This can happen to any woman no matter how long they’ve had a period.

      As for water weight – oh yes! Bloating and water weight are very common for women leading up to and during a period. Combat this by drinking plenty of water and exercise as much as you don’t feel like it – all this brings some relief.

      Hope that helps!

  3. PLEASE HELP i dont know how to tell my mom i started my period its ocword and im adopted and i dont feel confrontable so i have to sneak it all please help me!!

  4. What’s so funny about this is that I’m a registered nurse who went to college for four years and I only learned how to truly count your period a few months ago after doing some research on the internet.

    That goes to show how confusing it is! I used to just wear a pantyliner for a week and hoped my period would show up sometime around then. Now that I actually get how to track it, it comes within 2-3 days of when I predict it!

  5. May be a strange question, and hard to explain what I’m asking, but I’ll try : ) I have PCOS and have “regular” periods (at least for my body). I only get one period a year, but it’s religious and I always know when to expect it. My question is: Is my period cycle just an extremely elongated one, or does it kind of shut off? I have seen my doctor and gotten blood tests and everything done. I don’t experience a heavy or painful period, and it lasts a regular 5-6 days. I’m not concerned about it, but the whole cycle aspect of it got me thinking! Got any clues?

  6. How do we calculate the last day of period if the last few days are light ? I have a period app. But need to accuretely when my period ends so I know when I’m fertile. Thanks

  7. Thank you so much this helped alot I just now got my period tonight and I am 11 I probably should of paid I little more attention in 5th grade because I didn’t know what to do!!! So thank you soooo much

  8. hello i was wondering if there could be a chance that i could be expecting a child my last period was april i started the 25 iam always on time my face breaks out and then the month of may like the 20 i started breaking out so i thought my period would be in the next week it never came tell the first of june and i have never ever skiped a month iam really scared and my nevers are shot and advice any one can give me…?

    • Hi Patricia,

      I highly recommend you take a pregnancy test and see your doctor. That is the only sure way to confirm a pregnancy. Good luck!

  9. I never know when my period is going to come. I have been tracking my period for about two years and… there is no pattern. Once I didn’t have a period for four months (I’m gay, so I wasn’t scared of it being pregnancy), and then I had my period for a month straight. Or sometimes I have two 5-7 day periods in the same month (about a week in between). I’m not really sure what the hell it’s doing.

    • Hi Emsie,

      This is something you may want to see your doctor about just to get a better idea of what your body is up to.

      Good luck!

  10. It could be a nice very helpful bit of information. I will be glad that you just discussed this convenient data about. Remember to remain united states knowledgeable similar to this. Thank you for sharing.

  11. hii
    m suffring from thyroid in which m gaing w8 from last 1 year but now my report is ok
    on 2 may i got my period nd on june its not come yet my doctor gave me 7 days deviry medicine nd after that m taking autrin capsule nd today 19 june i got just a spot of blood my periods not coming properly what to do please help. (pregnecy test is negetive)

    • 5days after my period i had a anus sex intercourse with my partner,i went for a pregenancy test is negative is up to 24days my period has not yet,come

  12. hello, my last period was April 28 and lasted about 6-7 days (so til may 3) and then I had unprotected sex may 11. My period was supposed to come I’m guessing may 28-30 but it didn’t come. I am pregnant, but I wanna know if I got pregnant on may 11. I’m 95% sure because the weeks add up. I counted about 6 weeks but doctors add a week since they have a different calendar, so I’m 7 wks. But I also had sex on my period. I know it’s super rare to get pregnant on your period, so chances are I got pregnant may 11. The doctor said I did but I just want to double check

    Thank u!

    • Hi,

      Thank you so much for writing to me! Unfortunately I am not qualified to make this assessment. I would consult another doctor for a second opinion instead. Good luck!

  13. okay so i’m expecting a period on the 4th of July(no swimming for me) but i had intercourse 2 weeks prior to that date i took a test on today july 2nd and it came out negative but i still feel funny not nausea or anything like that my boobs aren’t sore or anything. i just feel funny. what could this be?

  14. Hi…. Pls i want to know the cause of these…. I dnt rili know, my menses comes instead of the normal 5days i have been hearing, mine comes 2days onli and its very very light atyms d 2day wil be onli in the mornin or evenin, and atyms it drops the 3rd day but just a drop. Pls wot could be the cause of these…

  15. I had sex last month and still had my period, are there still chances of me getting pregnant or seeing my period again this month?

  16. 5day after my period i had a anus sexualintercourse with myboyfriend,it 24days to day after myperiod have not seen the nextperiod now,i dot knew may be am pregnant now.please heip me out.

    • Hi Imani!

      Yes! That sounds completely normal. Your first couple years of having your period is a little irregular because your body is still getting used to having a period. It’s a big step and huge change for your growing body so sometimes it makes mistakes like getting your period a little early. Completely normal :)!

  17. Hey my question is I had my cycle on the 30th of June it lasted just over 9 days it ened on the 10th of july when I finished 2 days after me and my partner had stupidly had unprotected intercourse but then the day after I started needing lightly again which lasted a wk I have never had this problem and now I don’t know when I should be expecting my cycle

    • Hi! It depends how long your cycle is. Say your cycle is 30 days then your last period was July 10… then next period is on….. Aug 6 or 7.

      How many days is your cycle?

  18. Could i be pregnant if my period began on July 19,2013, i had a tablespoon of cycle on Aug. 6,2013 that lasted for about 2minutes and nothing since then? Im scared and confused right now, Help??

  19. my period came out on 1th of august then on 2nd nothing came out atall,on 3rd it started again and ended on 7th,i’m conffuse because i dnt know when to ovulate

  20. Hi Okay so I am freaking out!!!! I have my local fair that I am excited about I show in it and it is what I look forward the most to every year! But this year I am afraid that I am going to start my period during and that would not be fun at all! I was wondering if anyone could help me try to figure out or at least give me an estimate on when I should start my period?! I started on the 1st of June, and then I started again on the first of July. Then last month I started on the first of Aug. When do you guys think I will have my period next? I have been I guess a little stressed over it so I want to be able to relax over fair and not be running to the bathroom every 5 seconds to make sure that I haven’t started yet. Thanks

  21. I have a question. When determining when your period ends (or the last day)… lets say today I bleed very little and then tomorrow I stop bleeding. Do I count today as the last day or tomorrow?? I have an app on my phone and idk… i just wanna be accurate lol. My period’s been wacko this past month

  22. This completely scares me! I have period for around 4 years, and my period never comes earlier than 35 days! From last year onwards, my period starts to come at around 47days! I’m having olevel this year, so i’m in major stress, hence affecting my diet too. Is this normal?

  23. hi!

    i have a problem because i dont know when my menstruation is about to come.
    last august 1 i had my period it lasts 5 days then august 14 again lasts 5days too.
    now im still waiting for my menstruation to come i dont know what exact date it will come. it was the first time happened to me. i dont want to get pregnant yet. i have two kids my youngest is 4 months old. please help. thanks

  24. suppose to start my period tomorrow on the 22 can i still get today.????.i have had the pms signs what i get every month .crying You!!

    • Hi Louise,

      Yes it is possible. As much as we try to prepare, it can still take us by surprise. You can make sure you’re ready by keeping pads or tampons in your bag and by wearing a pantiliner.

  25. I had my period on August 17 which was normal. It lasted about 6 days… and then I started having It again on Sept. 3 and It lasted about 8 days..this was not normal…I saw my Dr and he didn’t seem worried…. can this affect my ovulation? I would be fertile about now if I hadn’t had that unexpected period. Now I am really confused

    • Hi Christine,

      Hmm to be honest, I’m not completely sure… I would direct your questions to your doctor again. Just ask him or her like you asked me and express your concerns for keeping track of ovulation :)!

      Usually when you are ovulating, your vaginal discharge is thicker so that may be a clue. It’s thicker so only the best sperm make it to your egg!

  26. I started my period on sept 31 and it lasted seven days I am trying to figure out when I will start again I always started at the end of the month but I haven’t started today any ideas

  27. Hi,

    Just after some advice – I have extremely irregular periods due to having PCOS. Just started only my third period of the year and was wondering what day exactly do you count from? Do you count from the first sight of ANY blood ie. from darker, brownish looking blood in really small quantities or from the vivid red blood in larger amounts? Same as when it finishes, do you count right up until the last bit of the darker blood or until the end of the bright red blood? There’s so many conflicting theories out there that I don’t think I’m getting it right. Would like to be sure.

    Many Thanks,
    Kate (:

  28. Hi . Since I was 18 I was told I had pcos me n my husband just purchaced our own house. We woukd like to start a family soo f0r 7yrs I had a non existant period. Or I would get it out of the blue like 2 or 3 times everyother year. Which means I’m not ovulating? Soo the last year I hVe bedn tracking my period since January 2013 n I’m surprised I had a period evey single month evey 28 days I finally feel like a woman! Does this meN I am ovulating? Or can I have my period evey month and NOT ovulate? Because we don’t use protection n still no pregnancy.I am going to see my dr in 2 weeks but I want answers now

  29. Hi! I have been having my period for 3 years. I have a sense of when it is coming, but it is sometimes wrong. I feel that my period is becoming irregular. Within those three years, I have missed several of my periods. Are there any tricks or methods to knowing when the next period will come.

  30. I started my period october 25 and its now december 3rd and I haven’t had one I’m nervous I took at test and it came up negative what do I do I always start at the end of the month like clock work my bf said my thighs and but were getting bigger and my boobs hurt but they usually do before I start can thet hurt cause I’m pregnant to please help me

  31. Hi! I’ve been counting my period cycle for almost a year now and not only is it very irregular but it also averages 41 days per cycle. Is this normal?

  32. hi, I began my period on dec. 2, ended around the sixth, now it is the 25th and I got a period like cramp, it didn’t last very long. I always get cramps before my period. Is this normal? It’s like a 23/24 day cycle, is it normal? Also I am sexually active but always protected and my boyfriend always tries to pull out and ejaculate inside the condom outside of me, is there a chance I am pregnant? Is this 23/24 day cycle normal? I’m fairly regular and got my period about 5 or 6 years ago

  33. i saw my period o the 26 of november 2013 and i was expecting my period on december 26th but it delayed and came out on the 31th of december 2013….please i really want to no when my ovulation date will be is very important to me…i will be expecting ur reply on my email please i need to get pregnant…thanks and God bless

  34. Im far from being a tennager, so I’m kinda shy to talk about this, I’ve always had painful periods. As in terrible pain but I’ve neva missed my period. So my ques is is it possible to have ur period twice and within 10 days interval. Dis is cumming @ a terrible tym! Help or do I have an infection or sumfin?

  35. I’m 14. I started my period for the first time a couple of months ago, but I’ve never once had a normal cycle. My cycle from the beginning has been about 14 days and each period lasts about 7 days. I also have super bad cramps. What’s wrong? Is this normal? And sometimes I’ll randomly bleed for one day in between… Help?

    • Hi Reilly, I used to get irregular periods, years after I started. I think it’d be best for you to talk to your doctor and get a referral to a gyno, just to get things checked up :) sometimes it takes a while for you to adjust when you first start, but talk to a medical expert.
      They really know their stuff!

  36. Okay so I’m not sure if I had my period or not, I have little blobs of like brownish and redish on my underwear. Is that my period or something else?

  37. Plz i had my period on the 9th of december 2013,i had another one on the 2nd of january 2014,when am i suppose to have another one.thanks

  38. Hi I’m Dakota, I’m 15 years old and i started my period at school it went threw my underwear and my pants and my friend told me because she could see it. I felt embarrassed because everyone saw it! and I Know when you will start your period I know a lot of stuff about periods so if you to contact me please email me @ Thanks

  39. Pls i saw my period january 16th which lasted for 4days and i had an unprotected sex on 25th of january. Pls am i likely to get pregnant?

  40. If you would like to figure out the specifics of your own menstrual cycle, there are a variety

    of online menstrual period cycle calculators available that can help you chart your own cycle.

    In addition, if you are pregnant, there are also due date calculators available online that can

    approximate your due date. In addition, your doctor can also help you confirm these timelines.

  41. I normally bleed for 6-7 days every month. So how do I calculate my fertile days. Last month I had bleeding between Jan 9-14. This month it was between the 9-15. So whats the length of my cycle and when are the fertile days and how do i calculate it?

    • A period is the days that you bleed. Your period is only one part of the menstrual cycle. The menstrual cycle lasts from the first day you bleed until the first day of your NEXT period. On average, this is 28 days. Mine is closer to 35 days.

      I know it is a bit confusing at first. Does this clarify it? Feel free to ask more questions gemstone!

      -The Period Blog

  42. Hi I’m 29 years I’m pregnant and I don’t know when I’m due because I had a normal cycle from the 19 to 31 jully 2013 then on the 11 to 14 august I had another period,I don’t knw when I got pregnant my cycle is usualy 23 to 25 days plz help I’m confused

  43. I’m abit stuck lol….I had a mc boxing day and had2 cyles since I had my period last month on 21st feb 2014 what’s my cycle and when wud I be due on again x

  44. am 23yrs old i dnt no hw to calculate ma cycle i did nt remember d date of my period dat ws january bt feb own ws 22th hv nt seen march period

  45. plz help me am confused, i ll make it simple, i had my period on 8-14 of dec 2013, i had sex on 27 dec 2013, i still saw my period on jan 2014 bt it was very late on 21-27, (i av a 28days cycle) on feb i saw it on 26 -1, ( it came late) and now being march i avn’nt seen it, plz help, am i pregnant? is it possible? …. urgent plz!! sm1 help me plz..

    • Hi Promxy,

      No it does not sound like you are pregnant especially since you have had two periods since the last time you reported having sex.

  46. plz help me am confused, i ll
    make it simple, i had my
    period on 8-14 of dec 2013, i
    had sex on 27 dec 2013, i still
    saw my period on jan 2014 bt
    it was very late on 21-27, “it was heavy”, (i
    av a 28days cycle) on feb i
    saw it on 26 -1,a bit heavy too, ( it came late)
    and now being march i avn’nt
    seen it, plz help, am i
    pregnant? is it possible? ….
    urgent plz!! sm1 help me plz..

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