The basics
How long is a normal menstrual cycle?
Most menstrual cycles last between 21 and 35 days, and about 28 days is the average. A period usually lasts 2 to 7 days, most often about 5, and loses roughly 20 to 90ml of blood in all. There’s a wide range of normal, and what matters most is what’s normal for you.
What does a normal period look like?
| What | Usual range | Source |
|---|---|---|
| Cycle length | 21 to 35 days, about 28 on average | NHS, ACOG |
| Bleeding | 2 to 7 days, usually about 5 | NHS |
| Blood lost | About 20 to 90ml in all, 1 to 5 tablespoons | NHS |
| When periods settle | Regular by 16 to 18 for most people | NHS |
There’s a wide range of normal. The NHS describes it like this:
- How often: every 21 to 35 days.
- How long: 2 to 7 days of bleeding, usually about 5.
- How much: about 20 to 90ml over the whole period, roughly 1 to 5 tablespoons. Some people bleed more than this.
Periods often take a few years to settle; most people have regular periods by 16 to 18. Near the end of your reproductive years they change again: menopause usually comes in the mid-40s to mid-50s, and the average age in the UK is 51.
What if my cycle changes?
A change in your periods doesn’t necessarily mean something’s wrong, but the NHS says it does need looking into. That’s where a log helps: dates and details make the conversation with a doctor quicker.
When should I see a doctor?
See a doctor if:
- Your periods become more painful, heavier or irregular.
- You bleed between periods or after sex.
- You’ve missed 3 periods in a row.
Frequently asked questions
Is a 35-day cycle normal?
Yes. The NHS counts gaps of 21 to 35 days between periods as within the usual range. Shorter or longer than that is called irregular, and is worth mentioning to a doctor.
When do periods become regular?
Periods often take a few years to settle. Most people have regular periods by 16 to 18.
How much blood is a normal period?
About 20 to 90ml over the whole period, roughly 1 to 5 tablespoons. Some people bleed more than this.
Sources
Seventh is a free period and cycle tracker for iPhone and iPad, by doogud. This article is general information, not medical advice. If something feels wrong, see a doctor.
