A period lasts 2 to 7 days for most adults, and the typical period length is about 5 days. Two days is normal and so is seven. Eight days, or a week that keeps turning into ten, is the point where a doctor wants to know.
This guide covers where those numbers come from, whether a 2-day or a 7-day period is anything to worry about, why periods get shorter or longer, how birth control changes them, and what to write down so an appointment starts with facts instead of a guess.
How long does a period last?
The NHS says a period can last between 2 and 7 days and usually lasts about 5, with the bleeding heaviest in the first 2 days. The American College of Obstetricians and Gynecologists says in its FAQ on abnormal uterine bleeding that a normal period generally lasts up to 7 days. Those two agree on the ceiling for a normal period length.
The biggest real-world dataset puts the average period length a bit lower. A 2019 study in npj Digital Medicine looked at 612,613 cycles logged in the Natural Cycles app and found a mean bleed length of 4.0 days, give or take 1.5. Bleed length there meant consecutive days of actual bleeding. Spotting didn’t count, and users were told not to log the light bleeding just before a period as the period itself.
That counting rule is worth borrowing. Day 1 is the first day of real flow, and the last day is the last day of real flow. Brown spotting the day before and the day after aren’t period days. Counted that way, a period that felt like it dragged on for nine days is often six.
Is a 2 day period normal?
Yes, if it’s your usual. Two days is the bottom of the NHS range, and the 600,000-cycle study found plenty of short bleeds. Cycles at the short end, 21 to 24 days, had periods half a day shorter on average than the rest, and bleeding got shorter with age across the whole sample.
The questions worth asking are whether it’s real flow and whether it’s new. Two days of bleeding that needs pads is a short period. Two days of brown spotting with nothing heavier isn’t a period at all, and if you could be pregnant it’s a reason to take a test. Spotting away from your period has its own set of causes, covered in our guide to bleeding between periods. And a period that has always been two or three days is a different thing from one that used to be five and dropped to two this year. The first is your normal. The second has a cause, and the causes are in the next section.
Why is my period so short?
The usual reasons are ordinary ones.
- Hormonal birth control. ACOG’s page on abnormal bleeding says hormonal methods change bleeding, and that the hormonal IUD and the injection may stop it completely after a year of use. The pill, patch and ring give most people a shorter, lighter bleed than they had before. This is expected, and it’s the reason doctors prescribe these methods for heavy periods.
- Age. The Natural Cycles study found an average of 4.2 days of bleeding at ages 18 to 24 and 3.7 days at 40 to 45. That’s half a day over twenty years, so a period that’s slightly shorter than it was at university is on schedule.
- Perimenopause. Past the early forties, periods can get lighter and shorter, or heavier and longer, and often alternate. Our guide to tracking periods in perimenopause covers which changes are expected and which need a check.
- An overactive thyroid. The Office on Women’s Health page on period problems says hyperthyroidism can cause fewer and lighter periods than normal. It usually comes with other signs, such as weight loss, feeling hot, or a fast heartbeat, and a blood test settles it.
- Stress and weight change. The same page says long-term stress and gaining or losing a lot of weight can affect the part of the brain that controls the cycle. That shows up more often as a late or missed period than as a short one, and our guide to why periods run late covers that side.
Book an appointment if you have three short periods in a row after years of longer ones.
Is a 7 day period normal?
Seven days is the top of the normal range, and a period that lasts a full week every month is a long normal period. ACOG says up to 7 days and the NHS says 2 to 7.
The line is just past a week. ACOG’s FAQ on heavy menstrual bleeding lists bleeding that lasts more than 7 days as one sign of heavy menstrual bleeding, alongside soaking through a pad or tampon every hour for several hours in a row, needing more than one pad at a time, needing to change during the night, and clots as big as a quarter or larger. The Office on Women’s Health puts the call-the-doctor line at a period lasting longer than 8 days. So a 7-day period is normal, an 8-day one is the edge, and 10 days is over it.
Why is my period longer than usual?
A period that runs past a week, or past your own usual, has a cause more often than a short one does. ACOG’s abnormal bleeding FAQ lists them.
- A cycle without ovulation. When ovulation doesn’t happen the lining builds up unevenly and sheds unevenly, which can mean irregular and sometimes heavy bleeding. ACOG names PCOS and an underactive thyroid as conditions where this happens, and it’s common in the first years of periods and in perimenopause.
- Fibroids and polyps. These are non-cancerous growths in or on the uterus. Both can make periods heavier and longer, and fibroids can also cause bleeding between periods.
- Adenomyosis and endometriosis. In adenomyosis the lining grows into the muscle wall of the uterus. Both conditions can cause heavy bleeding and period pain that gets worse over time. If pain is what you notice most, read tracking periods with endometriosis before you see a GP.
- The copper IUD. ACOG says it can cause heavier bleeding, especially in the first year. Longer periods in the months after a copper IUD goes in are expected, and they usually settle.
- Blood thinners and aspirin. Both can make periods heavier and longer. If you started one recently, tell whoever prescribed it.
- A bleeding disorder. ACOG says you may have one if your periods have been heavy since they first started, and the other signs are easy bruising, frequent nosebleeds, and gum bleeding after dental work.
A single long period after a missed or late one is common and usually means the cycle before it skipped ovulation. If a second and third long period follow, see a doctor. If you’re in the middle of one now, the guide to a period lasting 10 days or 2 weeks says how soon to be seen.
How long does a period last on birth control?
For most people it’s shorter than it was before, and sometimes it stops altogether. On the combined pill, patch or ring, the bleed in the break week is a withdrawal bleed rather than a period, and it’s typically lighter and shorter than a natural one. Progestin-only methods vary more. ACOG says the hormonal IUD and the injection may stop bleeding completely after a year, and in between they can produce irregular light bleeding that’s hard to count as a period at all.
The copper IUD goes the other way, with heavier and longer periods in the first year. If you’re choosing a method partly for what it does to your periods, that’s the one difference to know.
When to see a doctor about how long your period lasts
Book an appointment if any of these apply. This list combines the NHS, ACOG and Office on Women’s Health lists.
- Your period lasts more than 7 days, more than once.
- You soak through a pad or tampon every hour for several hours in a row, or need to change during the night.
- You pass clots larger than about 2.5cm, roughly a 10p coin or a quarter.
- You bleed between periods or after sex.
- After years of being the same, your periods have changed in either direction and stayed that way.
- You feel unusually tired, dizzy or short of breath during or after your period, which can mean iron loss from the bleeding.
- Your period is much shorter or lighter than usual and you could be pregnant.
The NHS says heavy periods are common and that help exists. If you’ve been told a week of soaking through is just how it is, know that it’s treatable.
How to track how long your period lasts
Write down three things and you’ll have what a clinician asks for. ACOG’s own advice is to note the dates, the length, and the type of bleeding on a calendar.
- The first and last day of real flow. Log spotting as spotting, on its own days, so it never moves day 1 or pads out the end.
- How heavy each day was. Light, medium or heavy is enough, and the number of pads or tampons on the heaviest day is better. Heavy for two days and light for three is a different period from heavy for five, even though both last five days.
- Anything that changed. That means a new birth control method, a new medication or a rough month. The cause of a short or long period is usually in that column.
Do that for three or four cycles and the question “is my period too long?” answers itself, because you’ll know what your normal is and whether this one left it. Our guide to keeping a period diary goes into what else is worth writing down, and our guide to cycle length covers the other number, the gap between periods, which changes for different reasons. Our period calculator turns those two numbers into dates for the next six cycles.
How Plum tracks period length
We build Plum, a period tracker for iPhone, so this is what it does with the numbers above. Marking a period day takes a tap, and each period day can be light, medium or heavy. Spotting is its own category, either red or brown, and you log it on its own days. So a day of brown spotting never becomes day 1 and never stretches the end of a period.
Plum uses your logged period days to work out how long your periods usually last, and it uses that alongside your cycle lengths when it predicts the next one. Flow is a logging category you can switch on if you want to record heavier and lighter days, and it sits on the same day as the period entry, next to pain, energy and whatever else you track.
Plum shows no ads and never sells personal data. It does require an account and syncs your data to our servers, encrypted in transit and at rest. If you share a cycle with a group, the group sees your period dates and nothing about how heavy any day was. If you’re still choosing, our list of good period tracker apps covers the others as well.
