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The Ultimate Guide to Measuring Your Period Flow



5 min read

Thinx Periodical The Ultimate Guide to Measuring Your Period Flow

by Morganne Skinner | 08/09/2023

When you go to your gynecologist and they ask if you have heavy periods, how do you respond? Most of the time, people think about what’s a normal flow for them.

While it’s great to be familiar with your body, sometimes what we think is normal for us isn’t actually normal or optimal. Maybe you never even knew there was a “normal” range for a period flow. That’s okay, because you’re in the right place. We’ll teach you exactly how to measure your period, what’s considered a normal flow, and why it’s important to measure yours!

what is a period?

While it may seem like everyone knows exactly what a period is, it’s important that everyone is on the same page so your measurements can be accurate.

A period is the term that refers to menstruation, or the days of bleeding that occurs following ovulation, when pregnancy does not occur. This is when the endometrium (uterine lining) sheds off and a new menstrual cycle begins. Days of spotting midcycle or leading up to the period do not “count” as days of your period. 

when does menstruation start?

Day one of your period (equivalent to cycle day one) is the first day of light, medium, or heavy bleeding. This may sound vague, but don’t worry — we’ll define these terms below! 

This means that days of spotting leading up to your period do not count as period days. But wait, I thought any day of bleeding was my period? Nope! 

Remember, during a period, the cause for the bleeding is the shedding endometrium. Spotting can have many, many different causes — such as (but certainly not limited to) an infection, inflammation, or polyps. 

why should I measure my period?

Most people know that a heavy period can be problematic, but the opposite is true too. It’s just as important that your period is heavy enough as it is that it’s not too heavy. Think of Goldilocks — we want it to be just right.

Why? Because the flow of the period tells us a lot about the endometrium. And what builds up the endometrium each menstrual cycle? Hormones! That’s right — estrogen and progesterone play very important roles in building a healthy endometrium. 

So when your menstrual flow is too light or too heavy, that’s a red flag for hormone imbalances. Your flow can also point to other health concerns, like anatomical abnormalities (i.e. fibroids), pathology (i.e. cancer or infection), ovulatory disturbances (i.e. anovulation), and other conditions (i.e. thyroid disorders and endometriosis). 

how to measure your period

Okay, now that we’ve gone through the definitions, let’s get into the period measurements! We’re going to define what light, medium, and heavy flows mean, objectively. These terms will be used to classify each day of your period. We’ll also discuss period products, like tampons, period underwear, and menstrual cups.

You’ll notice as we define the terms below, we include “mL” as a measurement. This quantifiable, numeric value is super duper important in measuring consistently. For that reason, we’ll give you a frame of reference for the amount of volume period products hold.

A regular tampon can hold 6 - 9 mL. A typical super tampon can hold 9 - 12 mL. When you are counting products to measure your flow, be sure to note what type of product you are using. The counts below are for regular tampons. Period products can hold varying amounts of mL depending on the brand, so make sure to check the package for the amount of volume each product holds.

light 🩸

Tampon: 1 - 2 regular per day 

Period underwear: 1 pair of lightest absorbency underwear per day

Menstrual cup: 5 - 10 mL per day

medium 🩸🩸

Tampon: 3 - 5 regular per day 

Period underwear: 1 pair of light absorbency underwear or 2 pairs of lightest absorbency underwear per day

Menstrual cup: 15 - 25 mL per day

heavy 🩸🩸🩸

Tampon: 6 or more regular per day 

Period underwear: 1 or more pairs of heavy or super absorbency underwear per day

Menstrual cup: 30 or more mL per day

how to start measuring

You’ll keep track of the number of period products you use each day (or mL in a menstrual cup), and then classify the day as light, medium, or heavy accordingly. 

For example, if you only had to use one super tampon in a day, your flow that day is light. If you had to use three super tampons in a day, your flow that day is heavy.  

what’s the difference between a light flow and spotting?

There are a few differences between spotting and light bleeding. One of the best ways to distinguish them is to pay attention to their consistency. Light bleeding will almost always be present when you go to the bathroom and wipe. Spotting on the other hand is more inconsistent and has a start/stop pattern.

Another indicator that you are spotting is that the flow is so light you don’t even need a period product or barrier. If the bleeding is only present on toilet paper, but isn’t making it onto your underwear, it’s likely spotting. For those who really like data, anything under 5 mL per day is considered spotting. 

what’s the normal amount of flow for a period?

The normal range for a period flow is 50 - 80 mL over the entire period. Anything below 50 mL is considered a light period, and anything over 80 mL is considered a heavy period. 

For example, a person with a three day period who has used 8 super tampons has a normal flow. A person with a seven day period who has used 12 regular tampons also has a normal flow. 

On the contrary, a person who uses 10 super tampons over a four day period has an abnormally heavy flow, as they’ve lost 100 mL during their period. Similarly, a person who uses five regular tampons per day over a five day period has a heavy flow, as they’ve lost around 125 mL during their period.

what if my flow is too heavy or too light?

Your menstrual cycle, including your period, is an indicator of your overall health. If you notice light or heavy periods, make sure to discuss your findings with your doctor, as they could be warning signs of a health problem. Your reproductive health is just as important as any other area of health — it deserves attention, too. 

Morganne Skinner, BSN, RN is a registered nurse, freelance nurse writer, and fertility awareness educator. She is the owner of the fertility awareness business Fertility Defined. She has seven years of nursing experience in rehabilitation, communicable disease, maternal child health, and in the surgical-trauma ICU. She served as a Peace Corps Volunteer for two years in rural Zambia, where her passion for public health and women’s health grew. She specializes in writing on topics such as health literacy, cultural communication, fertility, and women’s health.

At Thinx, we strive to provide our readers with the most up-to-date, objective, and research-based information. Our content is crafted by experienced contributors who ground their work in research and data. Articles contain trusted third-party sources that are either directly linked within the text or listed at the bottom to lead readers to the original source.


Institute for Quality and Efficiency in Healthcare. Heavy periods: Overview.

The American College of Obstetricians and Gynecologists. Heavy Menstrual Bleeding.

The American College of Obstetricians and Gynecologists. Abnormal Uterine Bleeding.

Cleveland Clinic. What’s the Best Tampon Size To Use?

Fertility Education & Medical Management. The Case for FEMM.

by Morganne Skinner

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