A typical period lasts 2 to 7 days, with most people bleeding for about 3 to 5 days. The total amount of blood lost is smaller than you might think: roughly two tablespoons (30 ml) across the entire period, though anything up to about 35 ml is considered normal.
What Controls How Long You Bleed
Your period starts when two hormones, estrogen and progesterone, drop sharply. During the first half of your cycle, estrogen causes the lining of your uterus to thicken. After ovulation, progesterone rises to stabilize that lining in case of pregnancy. When pregnancy doesn’t happen, both hormones fall, and the thickened lining breaks down and sheds. That shedding is your period.
How quickly your body completes this process determines whether you bleed for two days or seven. The thickness of the lining, how efficiently your uterus contracts to expel it, and how fast your blood clots all play a role. This is why your period length can vary slightly from month to month even when nothing is wrong.
What Your Flow Looks Like Day by Day
Most people notice a pattern: light flow on day one, heavier bleeding on days two and three, then a gradual taper. The heaviest bleeding typically happens within the first 48 hours. By the final day or two, you may see only light spotting or brownish discharge, which is older blood leaving the uterus more slowly.
If you’re soaking through a pad or tampon every hour for several consecutive hours, that’s not a normal heavy day. It’s a sign of abnormally heavy bleeding, which has its own set of causes worth investigating.
How Periods Change at Different Ages
If you’ve recently started menstruating, irregular and unpredictable periods are the norm, not the exception. During the first couple of years after a first period, many cycles happen without ovulation. Without the progesterone that ovulation triggers, the uterine lining can thicken excessively before shedding in an unstable way. The result is often heavier or longer bleeding and cycles that don’t follow a predictable schedule. It can take years for the body to settle into a regular 23- to 35-day cycle.
On the other end of the spectrum, perimenopause brings its own shifts. As ovulation becomes less reliable, periods may get shorter or longer, lighter or heavier, and you may skip months entirely. A consistent change of seven or more days in your cycle length is a common early sign. Once you’re going 60 days or more between periods, you’re likely in late perimenopause, heading toward menopause.
How Birth Control Affects Period Length
Hormonal contraception often makes periods shorter and lighter. Both the pill and hormonal IUDs can reduce bleeding significantly, and for some people, periods stop altogether. This happens because these methods keep the uterine lining thin, so there’s simply less tissue to shed.
The copper (non-hormonal) IUD is the exception. It commonly makes periods heavier and longer, especially in the first few months after insertion. If you’ve recently switched contraceptive methods and your period length has changed, that shift is likely related.
Exercise, Stress, and Other Influences
Intense physical activity can shorten periods or stop them entirely. This is most common in athletes and people who train hard on a regular basis, but it can also happen if you suddenly start a vigorous exercise routine after a long stretch of inactivity. The mechanism involves your body suppressing reproductive hormones when it senses high physical demand.
Chronic stress works through a similar pathway. Elevated stress hormones can interfere with the normal rise and fall of estrogen and progesterone, leading to lighter, shorter, or skipped periods. Significant weight changes in either direction can do the same, since body fat plays a direct role in estrogen production.
Signs Your Period Is Too Heavy or Too Long
The CDC defines heavy menstrual bleeding as periods lasting more than 7 days or flow that is unusually heavy. More specifically, you may have heavy menstrual bleeding if you:
- Soak through a pad or tampon every hour for several hours in a row
- Need to change protection after less than 2 hours
- Pass blood clots the size of a quarter or larger
- Bleed for more than 7 days consistently
Losing more than about 80 ml of blood per period (roughly 16 fully soaked regular pads or tampons across the whole period) is considered very heavy flow. At that level, you’re at risk for iron deficiency and anemia, which can cause fatigue, dizziness, and shortness of breath. Heavy menstrual bleeding has a range of treatable causes, from hormonal imbalances to uterine fibroids, so it’s worth getting checked rather than assuming it’s just how your body works.
Tracking What’s Normal for You
Population averages are useful, but your own baseline matters more. A 3-day period and a 6-day period are both perfectly healthy. What’s more informative is whether your pattern changes. If your periods have always been 4 days and suddenly stretch to 8, or if they become significantly heavier without an obvious reason like a new contraceptive, that shift is worth paying attention to. Tracking your cycle length, flow intensity, and duration for a few months gives you a personal reference point that makes it much easier to spot something unusual.