How much blood do you lose during your period?

    Updated 16 February 2022 |
    Published 23 November 2018
    Fact Checked
    Medically reviewed by Dr. Anna Targonskaya, Obstetrician and gynecologist
    Flo Fact-Checking Standards

    Every piece of content at Flo Health adheres to the highest editorial standards for language, style, and medical accuracy. To learn what we do to deliver the best health and lifestyle insights to you, check out our content review principles.

    Do you know how much blood loss during your period is considered normal? Or how to determine the amount of blood you’re losing each month? Don’t worry! This article will answer these questions and more. Read on to discover what is a “normal” period, and what to do if you suspect you’re suffering from abnormal menstrual bleeding.

    What is normal menstrual bleeding?

    Every woman’s period is different. In fact, one woman can experience many variations in her period during her lifetime. 

    Most women’s cycles last approximately 28 days, and their menstruations usually last anywhere between 3 to 7 days. Some women have naturally heavier periods. A perfectly normal period doesn’t exist; so, instead of focusing on whether your period is “normal”, you should learn the characteristics of your own cycle.

    Being familiar with the way your menstrual cycle works will make it easier for you to determine whether something isn’t right, or quickly discover any changes. You can use a menses calendar, like Flo, to keep track of your cycle.

    Your cycle should last anywhere between 21 and 35 days, and it should be somewhat regular. Having a cycle that varies a couple of days each month is normal, but anything longer than that could be cause for concern.

    How much bleeding is too much?

    Under normal conditions, menstrual blood loss only constitutes 2 to 3 tablespoons of blood each month. This amounts to approximately 30 to 50 milliliters. It’s normal to have heavier and lighter flow days during your periods. Heavier flow days usually occur at the beginning of your menstruation, and it tends to lighten as the days go by. Expelling some small clots is also considered normal.

    Menorrhagia occurs when a woman suffers from prolonged or excessive menstrual bleeding. Menorrhagia is usually defined as losing more than 80 ml or 5 tablespoons of blood during your period. You should also keep track of any period blood clots larger than 1 inch in diameter can be another indicator of excessive menstrual bleeding.

    Long periods can also be abnormal. If you period lasts longer than 7 days, you could still be experiencing menorrhagia. Polymenorrhea, on the other hand, refers to cycles that last less than 21 days, causing frequent menstruations. This is usually caused by anovulation.

    Any condition that causes menstruation to become too heavy, too long, or too frequent can make you lose blood cells, leading to anemia due to blood loss. Excessive menstrual bleeding is the main cause of iron deficiency anemia in women.

    How can I tell how much blood I'm losing?

    Now you know how many milliliters and tablespoons you should lose during your period, but how do you actually measure that in real life? It can be difficult to determine exactly how much blood is lost during menstruation. Fortunately, there are several tips that can help you determine the approximate amount of blood you’re losing. 

    Women tend to overestimate the amount of blood their menstrual blood loss. This is where math comes into play. Measuring the amount of blood you lose will depend on the type of hygiene product you use during your period.

    If you use menstrual cups

    This is probably the easiest way to measure your menstrual blood loss. Many cups include measuring marks, and you won’t have to account for any amount of blood absorbed by the product. Even if your cup doesn’t have any measurements, this information tends to be available online or on the cup’s packaging.

    Keep a log of how much blood your cup contains each time you remove it. If you use menstrual cups, it’s rather easy to calculate how much blood you lost throughout your entire period.

    If you use tampons

    Regular sized tampons absorb approximately 5 milliliters of fluid. Extra-absorbent tampons tend to hold twice that amount.

    However, it isn’t recommended to delay changing your tampons until they’re fully soaked. Instead, change your tampon every 4 to 6 hours. In order to calculate your blood loss during periods, keep track of how many tampons you use and how full they are when you change them.

    If you use pads

    Much like tampons, the absorbency of sanitary pads can vary between brands and models. However, most regular sized pads hold the same amount of blood that a tampon does — around 5 ml —. Similarly, extra-absorbent pads will hold approximately 10 ml of blood. When in doubt, check the package that your pads came in, since they’ll usually contain information regarding their absorbance.

    Once you know how many sanitary products you use during your period, you’ll need to determine how much blood you actually lost. During your menstruation, you’re not just losing blood. Other fluids, like mucus, can make up nearly 64% of your menstrual flow. That means that blood only makes up 36% of your flow.

    To calculate your actual menstrual blood loss, multiply the number of hygiene products you used during your period by 5 ml (in case of regular size products) or 10 ml (for extra-absorbent products). Multiply this number by 0.36 to get the approximate amount of blood you lost during your period.

    For example: if you used 9 extra-absorbent pads during your period, this equals 90 ml of total fluid loss. Multiply 90 ml by 0.36 — the percentage of blood in your menstrual flow —, and you’ll get 32.4 of actual period blood, which is well within the normal range.

    The difference between light, medium, and heavy periods

    Read medically reviewed articles on topics like this

    What causes scanty menstruation?

    Having a too-light menstruation can also be cause for concern. Some of the most common causes of light menstruations include:

    • Menopause: changes in the amount of menstrual blood loss can be the first sign of menopause.
    • Pregnancy: many women think that it’s impossible to get your period if you’re pregnant, but that’s not always the case. The bleeding that happens during an early pregnancy isn’t really a “period”, but it can match the date when you expect your menstruation. This can be caused by implantation bleeding, ectopic pregnancy, or threatened abortion. If you’re feeling sick on your period, consider taking a pregnancy test.
    • Breastfeeding
    • Stress
    • Eating disorders or malnutrition
    • Exercise
    • Polycystic Ovary Syndrome
    • Thyroid disorders.

    What causes heavy bleeding?

    Excessive menstrual bleeding is dangerous because it can lead to the loss of blood cells, causing anemia in women. Nearly a third of all women in reproductive age suffer from menstruation-related anemia at some point in their lives. Some of the most common causes of menorrhagia include:

    When is it time to schedule a visit with your practitioner?

    You’re the person who knows your body best, so consider going to a doctor if you detect any changes in your usual menstrual cycle. If you believe you are suffering from menorrhagia or hypomenorrhea, your doctor will be the best person to diagnose and treat the underlying cause.

    Depending on your symptoms, your doctor will perform a physical examination. They can also order imaging tests or blood tests to determine what is causing your abnormal menstrual bleeding. Once you have a diagnosis, they will also be able to prescribe treatment and other lifestyle changes to help you get better.

    Many causes of abnormal menstrual bleeding are treated through the use of hormonal contraceptives. If you’re suffering from anemia, your doctor could also prescribe supplements and dietary changes. A doctor or nutritionist will be able to advise you on what to eat after blood loss. These dietary changes could include eating more protein, citrus fruits, and leafy greens to improve your hemoglobin levels.

    There are many things that can cause abnormal menstrual bleeding. Whether your period is too light, too heavy, short, long, or irregular, it can cause distress and other physical symptoms.

    The easiest way to start dealing with any menstrual issues is by tracking your cycle. That way, you’ll have plenty of information for your doctor, and you’ll learn more about the way your body works.

    Abnormal periods are no fun but seeking professional help and getting the right treatment can help normalize your cycle and stop your menstruation from affecting your daily routine.

    History of updates

    Current version (16 February 2022)

    Medically reviewed by Dr. Anna Targonskaya, Obstetrician and gynecologist

    Published (23 November 2018)

    In this article

      Try Flo today

      Sign up for our newsletter

      Our latest articles and news straight to your inbox.

      Thanks for signing up

      We're testing right now so not collecting email addresses, but hoping to add this feature very soon.