A normal period lasts between 2 and 7 days, with most people experiencing about 3 to 5 days of bleeding. The total blood loss over that time is roughly 2 to 3 tablespoons, though it often feels like more. Your exact number of days can shift throughout your life depending on your age, hormones, stress levels, and whether you use hormonal birth control.
What Counts as a Normal Range
Anything from 2 days to 7 days falls within the medically accepted range for period length. Flow is usually heaviest in the first day or two and then gradually tapers off. You might notice bright red blood early on that turns darker or brownish toward the end as the flow slows. A period that consistently stays at 7 days or under and doesn’t require you to change a pad or tampon more often than every 1 to 2 hours is considered normal.
Your cycle length, meaning the gap from the first day of one period to the first day of the next, is a separate number. That typically falls between 21 and 35 days for adults, though teens can have cycles anywhere from 21 to 45 days while their bodies are still regulating.
How Period Length Changes With Age
Periods don’t stay the same from your first cycle to your last. In the first few years after getting a period, cycles tend to be longer (averaging about 30 days) and less predictable. Cycle length for people under 20 varies by an average of 5.3 days from month to month, according to data from the Apple Women’s Health Study run through Harvard. That means a teen might have a 26-day cycle one month and a 33-day cycle the next, and both would be normal for that stage of life.
By the mid-to-late 30s, cycles typically settle into their most consistent pattern. People in that age group see the smallest variation, averaging only about 3.8 days of difference between cycles. The overall cycle length also shortens slightly, averaging around 28.7 days for those 35 to 39.
Then, during perimenopause (usually starting in your 40s), things shift again. Periods may get longer or shorter, heavier or lighter, and the time between them becomes unpredictable. If the gap between your cycles starts varying by 7 or more days consistently, that’s often a sign of early perimenopause. Once you’re going 60 days or more between periods, you’re likely in late perimenopause, heading toward menopause.
Why a Period Might Last Longer Than 7 Days
Bleeding that regularly stretches beyond a week, or that requires changing a pad or tampon every hour or two, is considered heavy menstrual bleeding. Several conditions can cause this:
- Fibroids and polyps: noncancerous growths in or on the uterus that increase the surface area of the lining, leading to heavier and longer bleeding.
- Adenomyosis: a condition where tissue that normally lines the uterus grows into the muscular wall, often causing prolonged, painful periods.
- Irregular ovulation: when you don’t ovulate regularly, the uterine lining can build up too thick before shedding, producing a heavier, longer period. This is common in people with PCOS or thyroid problems.
- Endometriosis: tissue similar to the uterine lining growing outside the uterus, which can increase both pain and bleeding.
- Bleeding disorders: when blood doesn’t clot properly, periods can be significantly heavier and longer than average.
- Medications and devices: blood thinners and aspirin can extend bleeding. The copper IUD often causes heavier periods, especially during the first year of use.
Pelvic inflammatory disease and pregnancy-related causes like miscarriage or ectopic pregnancy can also produce prolonged or unusually heavy bleeding.
Why a Period Might Be Unusually Short
On the other end of the spectrum, some people consistently bleed for only a day or two. When this pattern lasts for several months, it’s called hypomenorrhea. It’s not always a problem, but it can signal a hormonal shift worth understanding.
Chronic stress is one of the most common triggers. Elevated cortisol disrupts the hormonal chain that controls your cycle, which can shorten or lighten periods. Significant weight loss works through a similar mechanism: your body needs a certain amount of fat to produce enough estrogen to maintain normal ovulation, and when that drops, periods can get shorter or disappear entirely.
An overactive thyroid gland can also make cycles lighter and shorter by throwing off the communication between your brain, thyroid, and ovaries. PCOS, despite being more commonly associated with heavy or irregular periods, can sometimes cause lighter flow because elevated androgen levels prevent ovulation altogether. And perimenopause, with its declining estrogen, can produce lighter periods before they eventually stop.
A less common cause is cervical stenosis, where the cervical opening is narrower than usual (sometimes from a prior procedure or infection), physically restricting blood flow out of the uterus.
How Birth Control Changes Period Length
Hormonal birth control is one of the biggest factors that can alter how long your period lasts, sometimes dramatically. Combination birth control pills taken continuously (skipping the placebo week) can reduce periods to once every three months. Some pill formulations are designed to eliminate periods altogether for an entire year.
Hormonal IUDs gradually reduce both the frequency and duration of periods over time. After one year with a higher-dose hormonal IUD, about 20% of users report having no periods at all. By the two-year mark, that number climbs to 30% to 50%. Even users who still get periods typically find them much shorter and lighter than before.
If you’ve recently started or stopped hormonal birth control, expect some irregularity for the first few months as your body adjusts. A period that’s shorter, longer, or absent during this transition doesn’t necessarily indicate a problem.
Signs Your Period Length Needs Attention
Variation from month to month is normal, but certain patterns are worth flagging. Bleeding that consistently lasts more than 7 days, bleeding that shows up in unusual patterns (like every week for a couple of days), or going 3 to 4 months between periods all warrant a visit to a gynecologist. The same applies if you haven’t started menstruating by age 16, or if you’re over 55 and still experiencing vaginal bleeding.
Severe cramps that appear suddenly after years of relatively pain-free periods are also a red flag. Menstrual cramps are common, but a notable change in their intensity can point to a new underlying condition like fibroids, endometriosis, or adenomyosis. Soaking through a pad or tampon every hour for several consecutive hours is another sign that bleeding has crossed from normal into territory that needs evaluation.