Menstrual blood loss… What’s normal?

Here is our myth-busting guide to help you know the difference between ‘normal’ and problematic ‘heavy’ menstrual flow, estimate your own fluid/ blood loss, and find out which underlying conditions can cause Heavy Menstrual Bleeding (HMB).

For all these facts and more- check out the ‘What’s normal? Myth-busting menstrual health e-booklet’- only £2.95!

1. How much blood/ fluid loss is ‘normal’?

Double espresso cup with coffee beans

Photo by Dominika Roseclay from Pexels

First off, you need to know something that you were probably never taught at school (even medical school!)- Which is that only approx. 50% of menstrual fluid is blood [1].

On average, people who menstruate lose ~ 70-80 ml of fluid (~ 35-40 ml of blood [1]) per period [2]. This amount of fluid would fill a double espresso cup (image on left) [3].

Half full clear plastic cup

Photo by Meir Roth from Pexels

In fact, anything up to ~ 160-170 ml of fluid (~80 ml of blood) per period falls within the ‘normal’ range [2]. This is because ~ 95% of all people who menstruate typically lose less than this amount [2]. This total amount of fluid would fill a tall (7oz) disposible plastic cup (image on right) [4].

Notes– variation is the norm when it comes to menstrual health- it is important to track your cycle for a while to work out what is the ‘normal’ range of experiences for you. This will help you to spot any significant or unusual changes in the future. Hormonal contraceptive medication is known to significantly reduce cyclical fluid/ blood loss in those with no underlying health issue [5].

What’s not normal?

Technically speaking, Heavy Menstrual Bleeding (HMB) is losing over 80 ml blood (~ 160-170 ml of fluid) per period [2]. Most people with this condition lose between 80- 200 ml of blood (160-400 ml of fluid) per period, but some people can lose even more than this [2].

Heavy Menstrual Bleeding (HMB) can also make the period last longer than a ‘normal’ one [6]. Most people have periods that last between 3-7 days, with at least 80% of the total fluid/blood loss happening on days 1-3 [6]. If your period typically lasts longer than 7 days, especially with significant fluid/ blood loss over more than just the first 3 days, you may be experiencing HMB [6].

Left untreated, HMB rapidly results in iron deficiency anaemia, and the awful thing is, anaemia makes periods even heavier [7]… It’s a truly vicious cycle! It is therefore important for clinicians to simultaneously treat iron deficiency anaemia alongside any other investigations/ interventions for Heavy Menstrual Bleeding [7].

2. How do you measure menstrual blood/ fluid loss?

We can roughly calculate blood loss by simply halving the total fluid loss… So this really depends on the collection method you prefer to use.

Menstrual cups now provide the easiest and most accurate way to measure fluid levels, since many of them come with a handy scale on the inside [8]. Others may just list their total capacity size, which still enables users to estimate how much fluid has been collected over the course of a period. Simply look at how much fluid is in the cup when changing it and note it on your phone, or on paper. Do this throughout the whole period, since diagnostic cut off points are based on total blood loss per period.

Disposable items, such as pads and tampons all have to meet the same absorbency standards [9]. This means that it is possible to roughly estimate fluid loss by counting how many tampons or pads you bleed through during your period.

The chart below shows the exact standard ranges [10], which are actually based on weight, rather than fluid level- but this is still a good way to roughly calculate fluid loss. For example, each (fully soaked) regular soaked tampon or pad ~ 7ml, each ‘super’ ~ 10ml, each ‘super plus’ ~ 13ml, and each ‘ultra’ ~ 16ml.

The problem is that many people change their pads and tampons before they are fully soaked, so the accuracy of this method is reduced – although it is possible to use a visual ‘pictogram’ scale to estimate fluid loss [11]. People also tend to use products with different levels of absorbency throughout their period, so it is important to note down the exact type of product used.

Ranges of absorbency in gramsCorresponding term
6 and underLight
6 to 9Regular
9 to 12Super
12 to 15Super plus
15 to 18Ultra

Pants on a washing lineWashable items, such as period pants, or washable pads may make estimating fluid loss more difficult, because there is no universal standard of absorbency for these items (yet). However, if you are concerned that you may be experiencing heavy bleeding, it might be worth using a cup for a few cycles, just to help you and your doctor make a more informed decision about possible treatment options?

Another less accurate, but practical guide is noting the number of times you have to change your menstrual underwear, cup, pad or tampon in a given time period. If you can answer yes to any of the following questions, you could well be experiencing Heavy Menstrual Bleeding (HMB) [12];

  • Do you have to wear tampons/ cups and towels together to prevent leaking through clothing?
  • Do you have to change items more than once every 2 hours?
  • Does blood ever soak right through your clothes, even though you are using a menstrual product?
  • Do you have to stay off work or cancel social engagements due to heavy bleeding?

3. What causes Heavy Menstrual Bleeding?

Note– It is very important that you seek medical advice if you experience a significant change in your period flow, or any mid-cycle bleeding.

Heavy Menstrual Bleeding (HMB) can be caused by various, and sometimes multiple, factors [13]. Luckily for us, the possible causes are listed in a handy acronym- PALM-COEIN [13].

a female abdomen with the words 'out of order' written in marker pen

Photo by Kat Jayne from Pexels

The first group (PALM) relates to structural problems- it is thought that growths in or around the womb increase the surface area of the womb’s lining (increasing the amount of tissue/ blood loss) and/ or interfere with the normal constriction of muscle and blood vessels involved in stopping menstruation (i.e. prolonging the period) [14]. These growths are categorised as; Polyps, AdenomyosisLeiomyoma (aka fibroids!), and Malignancy (e.g. womb cancer). By far the most common of these causes are fibroids and polyps, then adenomyosis, and only very rarely, more serious issues such as womb cancer.

The second group (COEIN) relates to non-structural problems: Coagulopathy (i.e. blood clotting disorders- approx. 13% of HMB cases are caused by these e.g. Von Willebrand’s Disease [15]), Ovulatory Disorders (e.g. hormonal changes associated with the peri-menopause, Polycystic Ovary Syndrome, thyroid or pituitary gland disorders), Endometrium (e.g. a blood clotting issue found only in the lining of the womb- usually diagnosed after excluding all the other possibilities), Iatrogenic (non-biological chemical factors- e.g. cigarette smoking, the copper coil (IUD), hormonal contraception, anti-convulsant, antidepressant, or anti-psychotic medications, and antibiotics such as rifampin and griseofulvin) and, lastly, Not Yet Classified (other gynaecological issues may play a role in HMB but are difficult to identify- this category will develop as further research is conducted) [13].

Treatment options obviously vary according to the cause(s), but it is definitely worth taking iron supplements regardless, since iron-deficiency anaemia plays a large part in the life-affecting symptoms of HMB (i.e. fatigue) and can further increase menstrual blood loss [7].

A bonus note for clinicians/ menstrual health and rights enthusiasts;

question mark made out of medical pills

Photo by Anna Shvets from Pexels

A few years ago, it was decided to just trust that people who sought help from their doctor for very heavy periods, really did have them [16]. This is actually a very nice intention; a decision to believe in female patients rather than dismiss them as ‘prone to exaggeration’ (which is sadly still a common experience). Unfortunately, menstruation education is typically of poor quality and so people who menstruate often do not have an informed idea if their flow is average, heavy- or even heavy enough to be Heavy Menstrual Bleeding (HMB).

It has been argued that it is better to treat all of those who think they have this condition, rather than measuring fluid/ blood loss or otherwise making a diagnostic distinction (e.g. asking the screening questions listed above) [17]. However, I am concerned that by doing this we are actually reinforcing a sexist myth that positions all menstruating people as debilitated (the medicalisation of menstruation), as well as normalising the exceptionally severe experiences of those few who really do lose over 80 ml of blood per period (the minimisation of serious women’s health issues).

The impact – Clinical research on HMB has found that a significant proportion (sometimes the majority) of trial participants, actually have ‘normal’ menstrual flow, which obviously messes up the findings [18]. Plus, the prevalence of Heavy Menstrual Bleeding can become highly exaggerated: A highly-cited UK study [19] simply asked people about their typical menstrual flow and roughly equated the subjective categories ‘variable’, ‘heavy’ and ‘very heavy’ with the sort of experiences described by people with HMB. Unsurprisingly, it reported an extremely high prevalence rate of debilitating blood loss in the UK population- around 25% [19]! This is not good for science or for society.

With menstrual cups, we now have a much simpler way to measure fluid loss/ estimate blood loss and so I think it is probably best to stick to the 160 ml fluid/80 ml blood loss categorisation, when deciding how best to treat an individual patient. For example, it may be that someone who has normal flow but feels it is ‘too heavy’ simply requires some further information about blood loss, how to manage periods, or perhaps even specific medical treatment for a different health issue (e.g. iron deficiency anaemia). They certainly should not be incorrectly categorised as having a serious health condition such as Heavy Menstrual Bleeding. Likewise, those who do have this condition, urgently require specific tests and specialist medical support, and should not be categorised as merely falling at the far end of the ‘normal’ curve when it comes to menstrual blood loss.

For all these facts and more- check out the ‘What’s normal? Myth-busting menstrual health e-booklet’- only £2.95!

Cite as: King, S (2020) ‘Menstrual blood loss… What’s normal?’ Menstrual Matters Blog accessed [date]

References and Notes;

[1] ‘Menstrual fluid’ is not the same as ‘blood’, menstrual fluid also contains beautifully silky cervical mucous and vaginal secretions. A high quality study found that typically, approx. 48-50% of menstrual fluid is blood and that “if total fluid volume is measured carefully, the estimate of actual blood loss is sufficiently accurate for clinical purposes“-Donoso, M. B. et al. (2019) ‘Normality Ranges of Menstrual Fluid Volume during Reproductive Life Using Direct Quantification of Menses with Vaginal Cups’, Gynecologic and Obstetric Investigation. S. Karger AG, 84(4), pp. 390–395. doi: 10.1159/000496608.

[2] The study that first determined an average blood loss of 30-40 ml, and 80ml blood loss as the 95th percentile cut-off point, was Hallberg L, Höegdahl AM, Nilsson L, Rybo G (1966): Menstrual blood loss – a population study. Variation at different ages and attempts to define normality. Acta Obstet Gynecol Scand 45:320–351 These findings were replicated in subsequent studies e.g. Scambler, A., & Scambler, G. (1985). Menstrual symptoms, attitudes and consulting behaviour. Social Science and Medicine, 20(10), 1065–1068, and Shaw Jr ST, Aaronson DE, Moyer DL. (1972) Quantitation of menstrual blood loss–further evaluation of the alkaline hematin method. Contraception 1972;5(6):497–513, and many others listed below.

[3] Ah yes, the age-old quest to visualise the amount of fluid lost during a period… I’ve opted for drinking vessels, since these are much more commonly used than egg cups or tablespoons! A double espresso cup typically holds 80ml of super strength coffee… The same as the average amount of fluid lost during a period!

[4] Yep, this time I went for the good old plastic cup. While it is crap for the environment and likely a product of horrific labour abuses, it does make a decent visual aid for describing the maximum ‘normal’ fluid loss approx. 170 ml/ 7oz.

[5] Davies, J., & Kadir, R. A. (2017). Heavy menstrual bleeding: An update on management. Thrombosis Research, 151, S70–S77. doi:10.1016/s0049-3848(17)30072-5

[6] Magnay, J. L., O’Brien, S., Gerlinger, C., & Seitz, C. (2018). A systematic review of methods to measure menstrual blood loss. BMC women’s health18(1), 142.

[7] See Percy, L., Mansour, D., & Fraser, I. (2017). Iron deficiency and iron deficiency anaemia in women. Best Practice & Research Clinical Obstetrics & Gynaecology, 40, 55–67. doi:10.1016/j.bpobgyn.2016.09.007 and Taymor ML, Sturgis SH, Yahia C. (1964) The etiological role of chronic iron deficiency in production of menorrhagia. JAMA 187:323–27.

[8] A recent study found menstrual cups to be an effective way to measure fluid loss- Donoso M, B, Serra R, Rice G, E, Gana M, T, Rojas C, Khoury M, Arraztoa J, A, Monteiro L, J, Acuña S, Illanes S, E: (2019) Normality Ranges of Menstrual Fluid Volume During Reproductive Life Using Direct Quantification of Menses with Vaginal Cups. Gynecol Obstet Invest 84:390-395. doi: 10.1159/000496608

[9] Disposible product manufacturers were forced to standardise their absorbancy levels after Procter and Gamble’s ‘Rely’ tampon – Toxic Shock Syndrome scandal in the late 1970s (resulting in several deaths and thousands of infections)- see Vostral S. L. (2011). Rely and Toxic Shock Syndrome: a technological health crisis. The Yale journal of biology and medicine84(4), 447–459.

[10] The FDA menstrual product absorbancy standard is written in full here- 

[11] For more information on the ‘pictogram’ method of estimating blood loss see; [5] [6] above or Quinn, S. D., & Higham, J. (2016). Outcome measures for heavy menstrual bleeding. Women’s health (London, England)12(1), 21–26.

[12] These are the questions advised by the NHS information standard on heavy menstrual bleeding-

[13] Munro, M., Critchley, H., & Fraser, I. (2011). The Flexible FIGO Classification Concept for Underlying Causes of Abnormal Uterine Bleeding. Seminars in Reproductive Medicine, 29(05), 391–399. doi:10.1055/s-0031-1287663

[14] Hapangama, D. K., & Bulmer, J. N. (2016). Pathophysiology of heavy menstrual bleeding. Women’s health (London, England)12(1), 3–13.

[15] Shankar M, Lee CA, Sabin CA, Economides DL, Kadir RA. (2004) von Willebrand disease in women with menorrhagia: a systematic review. BJOG. 111:734–740.

[16] NICE. Clinical Guideline 44; Heavy menstrual bleeding 2007. National Institute for Health and Clinical Excellence (NICE); Available at: [Ref list] [17] Warner PE, et al. (2004) Menorrhagia II: is the 80-mL blood loss criterion useful in management of complaint of menorrhagia? Am J Obstet Gynecol 190(5):1224–9.

[18] “The percentage of women with self-perceived HMB and a measured MBL of 80 mL or more was assessed in nine studies and found to range from 26 to 76%” – Magnay, J. L., O’Brien, S., Gerlinger, C., & Seitz, C. (2018). A systematic review of methods to measure menstrual blood loss. BMC women’s health18(1), 142.

[19] [Bad science alert!] Shapley, M., Jordan, K., & Croft, P. R. (2004). An epidemiological survey of symptoms of menstrual loss in the community. The British journal of general practice : the journal of the Royal College of General Practitioners54(502), 359–363.

Categories: No pain, Underlying conditions and What's normal?.


  1. Hello

    I read this article with great interest.
    Finally I have found an article that makes some sense of understanding what some ‘medics’ dismiss as ‘abnormal-normal’ for women to experience.

    My health journey with menorrhagia has been going on for approximately 18 months with having a TCRF in September which hasn’t helped. The bleeding and symptoms are worse than before. I have endured 6 months of severe menorrhagia with bleeding over 180 ml plus in 24 hours when measuring. I have no quality of life and I’ve waited over 7 months to seen OB/GYN.

    During this time I have received 3 IV iron infusions which I found I am allergic to and therefore cannot take the same brand. I am currently waiting for another, which has been mentioned to be urgently required, 4 weeks I’m still waiting.

    I feel that my situation is common in the way that women are treated in this regard, however I fear that my situation is very uncommon and has not been given the due care and attention it deserves. In the meantime, I continue struggling daily and sometimes I cannot even leave my home.

    More research is required to understand the symptoms and issues of women who don’t fit into the norm. I’m very dissatisfied and disillusioned by the lack of attention this serious condition is given in general by the medical profession.

    • SallyMM1

      This sounds horrendous- I’m so sorry that you are having to go through this. It sounds like the TCRF (Trans-Cervical Resection of Fibroids) either went a bit wrong or was insufficient to manage the fibroid bleeding? Have you been told anything about this? I wonder if you have been given any info about the Mirena IUS (a plastic device inserted into the womb)- it typically prevents menstrual bleeding and is a contraceptive (so no good if you are actively trying to conceive- but otherwise a great option), which would help you to recover your iron levels/ energy/ mood much more efficiently than simply taking supplements (especially if you are allergic to some of these!)? I would maybe recommend that you also make an appointment to discuss your options with someone from a family planning/ sexual health clinic- who will have more experience and knowledge about your options than a typical GP. You are quite right about the lack of adequate care and attention to these sorts of problems. If a male patient were as anaemic as you probably are, they would be admitted to hospital – whereas you are left waiting way too long for urgent care and treatment. I guess that the pandemic is playing some role in the delay but even still, this is not good enough. I hope you get some support really soon.

  2. KJB

    I read this article with great interest. I am a 42 year old and have suffered heavy periods for too many years to count. Only alleviated by a decade or so by the combined pill. I then spent a decade attempting and finally succeeding in having two children. Both attempts were long and difficult to achieve and I am convinced I have a reproductive/ menstrual issue which compounded it. For my second child I was told I wasn’t producing enough progesterone and therefore not ovulating despite everything about my very heavy menstrual cycles suggesting otherwise. I generally lose around 400-600ml of fluid/blood in a cycle, with the majority being in the first 48-72 hours. I know this because I now have to use a cup since no sanitary ware is able to accommodate my needs until day 3/4. It is exhausting and draining and impactful for those 3 or 4 days every month. I’ve complained many times to several GP’s over the years. I was brushed off completely in my 30’s as wanting children and therefore just had to put up with it. Now it’s only contraception aids offered that in theory can help though I am reluctant to mess around. I’ve never been offered any other form of help. I dread the idea of another 10 years of this. GP’s need to understand that when a woman complains she knows her own body and they should take it a lot more seriously.

    • SallyMM1

      I’m so sorry to hear this. Have you ever been tested for a blood clotting disorder? Your blood loss certainly indicates an underlying health condition of some sort. The Mirena coil can completely stop bleeding so is worth discussing as an option with your GP or sexual/ reproductive health nurse or doctor? It tends to have fewer side effects than the oral pill/ injection/ implant, too. I really hope somebody takes your problem seriously, finally.

    • MM

      I’m really sorry to hear this. There are some treatment options available. Please do not dismiss ‘contraceptive aids’ such as the Mirena IUS without fully discussing it with your GP or someone who has one fitted- it is a really effective and well tolerated option for many people in your situation. It can be life changing (in a positive way!). Your GP might be willing to refer you to a specialist who will have more time and experience to discuss your wishes and the various different approaches to treatment? You are probably anaemic- which makes periods even heavier- so definitely start taking iron supplements if not doing so already. I hope you find someone to listen to your concerns properly soon. Let us know how it goes.

  3. Marissa Claudio

    This article made me worry profoundly. During my heavy days I lose almost 2 ounces every 3 hours. It’s very easy to measure when I use menstrual cups and flex disks. I’m already on iron supplements and dont get cysts.

    • SallyMM1

      If you are managing your blood loss without any symptoms, then there’s no need to worry! If you do feel tired, irritable, or the blood loss increases, then it may be worth getting checked out by a doctor.

  4. Jamie

    I just started using a cup for this last cycle. I’m currently on day 12 of my menses. I didnt start tracking until day 6 and have already lost 230ml of fluids. My last two cycles were just as long and just as heavy. I had an ablation two years ago to help alleviate the pain and heaviness but that only helped for about two cycles. My paps all come back normal although everytime I’m seen my oversized uterus is mentioned. I will be making yet another appointment next week to hopefully get some answers, but I have to say that this is truly exhausting.

    • MM

      I’m so sorry to hear this. It is sometimes impossible to find the cause of heavy menstrual bleeding- but they should examine you beyond pap smears- ask for an ultrasound and blood clotting disorder tests if they find no physical abnormalities. The good news is that there are treatment options. If you are not trying to conceive then the Mirena coil can completely stop periods and is well tolerated by most people. Iron supplementation is probably also be required since you are likely anaemic – I can recommend the ‘fizzy’ tablets made by Feroglobin- as easy on the digestive system and with a decent dose of iron per tablet (and affordable). I hope you get to see a specialist and get some answers/ treatment options soon.

  5. Vic

    I can really relate to this. l have lost 400ml within the last 24 hours and have a history of HMB seemingly with little effective way of dealing with it. I had a laparoscopy and some fibroids were discovered. I don’t want an ablation as I have heard too many horror stories. My body rejected the Mirena coil within a week. I take Tranexamic Acid which has little impact. It’s stressful as it prevents me from doing things I want to do. I couldn’t leave the house to see my hairdresser this morning – which sucks because my roots are insane! 🙂

    Joking aside, I really understand where you’re all coming from. It’s intolerable sometimes, especially when you’re up half the night changing soaked pads and emptying cups.

    Sending you all solidarity. ♥️

    • MM

      I’m so sorry to hear this. So many people seem to be struggling with heavy menstrual bleeding. New research came out last week that found the Mirena and other progestin coils work really well for 75% of people using them for HMB, but the remaining 25% ultimately got endometrial ablation anyway. The good news is that ablation seems to be highly effective for most people- but yes, it is an ‘invasive’ procedure and not without potential negative side-effects/ risks. Do be mindful of your iron levels- this can make a big difference to quality of life/ mood/ energy levels. There is some new research looking at alternative medication interventions for HMB- but I’m not sure this would help such massive blood loss as yours (have you been tested for a blood clotting disorder- e.g., Von Willebrand’s disease?)- but here’s a link FYI

  6. Tiffanni Bennett

    I’m 42 years old. I have had very heavy periods for over 20 yrs. I had my tubes tied 17 yrs ago. My doc never told me of any other concerns after I got my tubes tied. My issue as well is I’m old fashioned and don’t use cups. I use super plus tampons and wear 2 over night heavy absorb pads and I still have to change then ever 2 hours. When menstruating I suffer with back aches, headaches and very tired. I spend most of my time lying in bed, because I can’t stand up with out feeling dizzy. You talk about clotting. When I change my tampons every 2 hours sometimes there’s a blood clot attached that’s bigger than the tampon. Since I have my tubes tied and dealing with this issue for 20 years, what health concerns should I be concerned about?

    • MM

      I’m sorry you have been left to ‘cope’ with this without proper advice. I think you need to arrange an appointment with a doctor as soon as possible. You may have a condition known as Heavy Menstrual Bleeding, or another gynaecological condition (fibroids, polyps, adenomyosis, etc.)- plus you are likely to have iron deficiency anaemia from all the blood loss. There are good treatments available to stop the bleeding altogether (e.g. the Mirena IUS) and you will probably need to take some iron supplements to get your energy back, too. Good luck and I hope you receive support soon.

  7. Elle Redmond

    I’ve recently been struggling with iron deficiency anemia and that’s when I realized that my periods were not “normal”. I started using a menstrual cup 2 years ago and I have to change it 4-5 times a day and use heavy pads. I started my cycle yesterday and I’ve already lost 104ml of fluid. I used to joke to my mom about needing blood transfusions after my periods, but now it’s not so funny anymore.

    • MM

      You may wish to see a doctor – heavy menstrual bleeding is never ‘normal’ and is typically caused by an underlying condition- such as fibroids, a blood clotting disorder, or polyps… Do seek help for this, as well as the anaemia- you may need to ask for a referral to a specialist? Good luck.

  8. Elle Redmond

    I’ve recently been struggling with iron deficiency anemia and that’s when I realized that my periods were not “normal”. I started using a menstrual cup 2 years ago and I have to change it 4-5 times a day and use heavy pads. I started my cycle yesterday and I’ve already lost 104ml of fluid. I used to joke to my mom about needing blood transfusions after my periods, but now it’s not so funny anymore. 💔

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