Top things to know:
A normal amount of menstrual fluid loss per period is between 5 mL to 80 mL
Different birth control methods may affect the heaviness of your period
Losing over 80 mL of menstrual fluid per period is considered heavy menstrual bleeding
Your period is a normal and healthy part of the menstrual cycle. It is the shedding of the endometrium (the lining of the uterus) that grows each cycle to support a potential pregnancy. The first day of your period is the first day of your menstrual cycle.
Changes to your period
Periods fluctuate for a while after they first start (menarche), after pregnancy, and as they come to an end (perimenopause). Not ovulating regularly — anovulation — is common during these times, and is a common cause of temporarily absent or heavy menstrual periods (1,2). If you don’t ovulate each cycle — you may miss a period, or it may come later than usual, and/or be heavier or lighter and/or shorter or longer than your normal period (1).
In between these life stages, your period should generally be about the same length and volume each cycle. You may still notice some changes though — the heaviness and length of your period depends on your hormones, which can fluctuate. Hormones can change temporarily because of things like stress, exercise, diet, or taking an emergency contraception pill (the morning after pill) (3-6). Every period is different, just as every body is different.
Periods and uterine bleeding can also fluctuate because of certain health conditions, like uterine polyps, fibroids, or PCOS — conditions that should be addressed with your healthcare provider. Certain bleeding conditions, medications, and infections can also affect menstrual bleeding, and cause irregular spotting (7).
If you use hormonal contraception, your period/bleeding patterns may be different.
Estimating the volume of your period
It is difficult to figure out how much menstrual fluid leaves your body every cycle. If you use a menstrual cup, these often have volume measurements (ex. 10 mL, 15 mL, 25 mL) indicated on the side of the menstrual cup to help you estimate how much fluid you have lost.
In general, the amount of fluid lost can be estimated when using pads or tampons, depending on the size and soaking amount of the menstrual product. A fully saturated light tampon can hold up to 3 mL of fluid, while a fully saturated super tampon may hold up to 12 mL (3,8). A regular daytime fully soaked pad may hold around 5 ml of fluid, and fully soaked overnight pad may hold 10-15 mL (3,8).
If you are repeatedly soaking through a tampon or pad every two hours, this is considered heavy menstrual bleeding and should be brought to your healthcare provider’s attention.
What is the normal period volume for people *not* on hormonal birth control?
Adult period volume
An adult period usually lasts up to 8 days (9). Across the length of your period, it is normal for between 5 to 80 ml (that’s up to 6 tablespoons) of menstrual fluid to leave your body (10).
The heaviest days of menstrual bleeding are usually at the beginning of the menstrual cycle (around the first and second day) (10). During the heaviest days of your menstrual cycle you may notice clumps or clots in your menstrual fluid—this is normal. The color of your menstrual fluid may also change as you progress through your period, with bright red blood being more common as flow is heavy, and darker shades when your flow approaches the end of your period.
Adolescent period volume
The amount, length, and frequency of periods around the time of menarche can vary greatly. It’s common for cycles to be somewhat irregular for a few years after your first period. As you progress through adolescence, period amounts and cycles become more regular, but may still be somewhat variable (2,11).
Adolescent periods can also be up to 80 mL per period, like the adult range, but are often lighter (2).
What is the normal “period” volume for people on hormonal birth control (e.g. the pill, the ring, the patch)?
Hormonal birth control (HBC) options like the pill, vaginal ring, or patch control the release and regulation of hormones like estrogen and progesterone within your body. When used correctly, the hormones in HBC prevent your ovaries from preparing and releasing eggs (ovulation).
Your period will change depending on the type of HBC you use. Bleeding typically happens during your “no hormone” days (when you take placebo pills, or the times in between new rings or patches). The bleeding you experience while using hormonal birth control is called withdrawal bleeding, and is not considered a menstrual period. Withdrawal bleeding is caused by the decline in reproductive hormones in your body during days when you get low or no hormones from your pill, patch, or ring (10,12).
Many people experience lighter bleeding and some don’t bleed at all while using hormonal birth control (13). When affected by hormonal birth control, the lining of your uterus doesn't thicken as much as it does without hormonal birth control. This typically results in lighter, shorter, or occasionally absent “periods,” especially for people who have been using hormonal birth control for many months or years.
What is a normal “period” volume for people on progestin-only birth control (e.g. the mini pill, the shot, the implant)?
There are many different types of hormonal birth control, all containing differing types and levels of hormones. Some types of birth control do not contain any estrogens and only contain progestin—a synthetic form of progesterone (14). These methods include progestin-only pills (the mini pill), progestin injections (the shot), or progestin implants (14).
When using progestin-only birth control pills, you may not have a typical menstrual cycle. Some progestin-only pills suppress ovulation, but it depends on the type (14). Bleeding can vary a lot on progestin-only contraceptives. Changes in period amount happen in response to the changes in hormones. These hormones affect the growing and shedding of your uterine lining.
Many people experience irregular bleeding, reduced bleeding, shorter cycles, or amenorrhea (no menstrual period) with progestin-only pills, especially when pills are not taken at the same time every day (15).
The shot and the implant
Methods like the contraceptive injection and the implant suppress ovulation (16,17). Most people who don’t ovulate due to these progestin-only contraceptives experience shorter, lighter, or occasionally absent bleeding days, though this doesn’t always happen (14).
Unpredictable bleeding, spotting, and prolonged bleeding are common when using these methods, especially during the first few months (18). These symptoms usually improve with time, but they can continue for some people.
What’s a normal period amount for people with intrauterine devices (IUDs)?
The hormonal IUD
While using the hormonal IUD, it’s common to experience irregular bleeding or lighter bleeding, and some people don’t bleed at all (14,19,20). This happens because the endometrium doesn’t thicken as much as it does when you’re not using hormonal birth control. This typically results in lighter or occasionally absent bleeding, especially for people who have been using the hormonal IUD for many months or years (14).
The copper IUD
Copper IUDs are non-hormonal, so you will experience the same fluctuations of estrogen and progesterone across your cycle as you did when you weren’t using a copper IUD.
Many people experience an increased amount of menstrual flow and longer period length while using the copper IUD, especially in the first 6–12 months (14,21). This may happen due to vascular changes and changes to blood flow in the uterus (20,22-24). Bleeding may be accompanied by an increase in large clots and cramping.
It’s also important to track any bleeding that happens at other times in your cycle outside of your period. This is known as spotting and can be caused by a variety of reasons including hormonal birth control (HBC), ovulation bleeding, or other physiological reasons (3,25). If you experience spotting on a regular basis, talk to your healthcare provider as they may need to adjust your birth control (if you are using HBC) or investigate to find a cause. Spotting is common in the first weeks of pregnancy, and can also be caused by certain infections and physical changes, which should be addressed with a healthcare provider (7,26,27).
When should you seek help from your healthcare provider about your period heaviness?
If your period amount is regularly over 80 mL, your period is longer than 8 days in length, or if your menstrual flow is so heavy that you are repeatedly soaking through a pad or tampon every two hours, this is considered heavy menstrual bleeding, and should be discussed with your healthcare provider (9). This type of excessive menstrual bleeding can impact a person’s quality of life and can cause anemia (28-30). Heavy menstrual bleeding can have many potential causes including: fibroids (abnormal growth of muscle tissue on your uterus), adenomyosis (a condition where endometrial tissue invades into the muscular wall of the uterus), problems with blood clotting (ex. Thrombocytopenia or Von Willebrand disease), uterine polyps (abnormal growths on the inside of your uterus), and (rarely) tumors (31,32).
If your period has stopped and you are not taking any form of hormonal contraceptive, you should also discuss this with your healthcare provider, as you could be pregnant.
Even if your period falls out of the “official” normal range, it’s important to know what is “normal” for you. The majority of health research is conducted on populations from western industrialized countries, which may not reflect your own personal genetic background or environment. Everybody is different, just as everyone's period is different. Speak to your healthcare provider if you are concerned about your period volume.