Top things to know:
A typical period length for someone who’s not using hormonal birth control or an IUD is 8 days or less
Hormonal birth control methods like the pill, patch, ring, or IUD often make period lengths shorter
Copper IUDs may make period lengths longer
The length of your menstrual period is the number of continuous days of bleeding within each of your menstrual cycles.
Your menstrual period is the shedding of your endometrium (the lining of the uterus). During your period, blood and endometrial tissue flow down through your cervix and vagina. The first day of your period is considered the first day of your menstrual cycle.
Periods are a healthy and common part of the menstrual cycle. But prolonged or heavy periods are associated with iron deficiency, which can lead to anemia and/or feeling unwell (1-3). Long or heavy periods may also be one sign of a health condition that should be addressed with a healthcare provider. It is possible to have heavy menstrual bleeding even when your period length is within range.
Short periods are generally less of a concern, but may be an indication of a health condition in some cases. A sudden, short period may also sometimes be spotting from a pregnancy (4).
If your period is irregular or prolonged, speak to your healthcare provider. It could be due to many underlying health conditions, such as polycystic ovarian syndrome (PCOS), fibroids, uterine polyps, or bleeding disorders (3,5).
What is the typical period length for people *not* on hormonal birth control?
Adult period length
For an adult who is not using any form of hormonal birth control or IUD, a typical period length is up to 8 days (6).
The first two days of the period are usually the heaviest flow, with the latter days having progressively less blood (7). Variations between differing period length and cycle lengths are common, as your period changes over your reproductive life (7,8). If your period length is regularly longer than eight days, consult your healthcare provider (6,7).
Adolescent period length
The period length of adolescents around the time of menarche, the first menstrual period, can vary greatly. It’s common for cycles to be somewhat irregular for a few years after your first period. This means your periods may not always come at the same time every cycle, and they may be somewhat different cycle-to-cycle. As you progress through adolescence, period lengths and cycles become more regular, but may still be somewhat variable (9,10).
A typical period length for an adolescent usually ranges between 2 to 7 days, but may sometimes be longer or shorter (9).
What is the typical “period” length 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 your HBC prevent your ovaries from preparing and releasing eggs (ovulation).
Your number of bleeding days and cycle length will depend 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 (6,11).
Many people experience lighter bleeding and some don’t bleed at all while using hormonal birth control (12). 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.
Some people also decide to skip any bleeding while using HBC, by skipping over the “no-hormone” days. Some hormonal birth control options have a cycle that mimics a typical cycle length (usually 28 days), while other types of hormonal birth control are continuous, which limits bleeding to once every three months, or even once a year (11).
What is the typical “period” length 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 progestins—a synthetic form of progesterone (13). These methods include progestin-only pills (the mini pill), progestin injections (the shot), or progestin implants (13).
Bleeding can vary a lot on progestin-only contraceptives. Changes in period length and heaviness happen in response to the changes in hormones. These hormones affect the growing and shedding of your uterine lining.
Methods like the contraceptive injection and the implant usually suppress ovulation (14,15). Some progestin-only pills also suppress ovulation, but it depends on the type (13). Most people who don’t ovulate due to progestin-only contraceptives experience shorter, lighter, or occasionally absent bleedings days, though this doesn’t always happen (13).
Unpredictable bleeding, spotting, and prolonged bleeding are common when using these methods, especially during the first few months (16). These symptoms usually improve with time, but they can continue for some people.
What’s the typical period length for people with intrauterine devices (IUDs)?
Your period on 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 (8,13,18). 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 (13).
Your period on the copper IUD
Many people experience heavier and longer bleeding while using the copper IUD, especially in the first 6–12 months (13,19). This may happen due to vascular changes and changes to blood flow in the uterus (18,20-22). Bleeding may be accompanied by an increase in large clots and cramping. Using nonsteroidal anti-inflammatory drugs (NSAIDs) may help reduce bleeding and pain (13).
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.
Prolonged or irregular bleeding on birth control
Starting a new method of birth control can cause changes the amount of days you bleed. Irregular bleeding is common when starting a new birth control method and usually goes away within three months.
Be mindful of how your bleeding days change and how you feel on an new form of birth control. Different brands and types of hormonal birth control contain different levels of reproductive hormones, so some brands or types may be better suited for you than others. Talk to your healthcare provider about trying another brand if you have continued spotting three months after starting a new method, or if your bleeding has gotten heavier (3).
Prolonged bleeding on hormonal birth control can also be caused by underlying health conditions such as uterine fibroids or an untreated infection (3,23).
If you suspect that your period is prolonged or irregular, speak to your healthcare professional. When talking to your healthcare provider, show them your tracking history. Also tell them if you’ve recently noticed unexpected changes in your body, such as unexplained abdominal pain, difficulty controlling your weight, or unusual hair growth on your face or body. This can help them identify what might be causing your long periods (13).
Why periods vary
The length of your typical period is determined by your age, genes, health, body mass index (BMI), behaviors, and birth control methods (23).
If you’ve had your period for a few years, it should generally be about the same length and volume each cycle. You may still notice changes from time to time— the heaviness and length of your period depends on your hormones, which can fluctuate due to factors like diet, stress, or taking an emergency contraception pill (the morning-after pill) (1,25-27).
Periods can fluctuate in cycles where ovulation doesn’t occur. This is why periods can fluctuate during adolescence, after giving birth, during breastfeeding, and during perimenopause (the menopausal transition) (28,10). People are less likely to ovulate consistently during these times.
Exercise, smoking cigarettes, and drinking alcohol may also affect period length and heaviness (29-34).
Download Clue to track your menstrual period.