Periods typically occur every 21 to 35 days for most people, with an average cycle length of about 28 days measured from the first day of one period to the first day of the next.

Normal Cycle Range

The menstrual cycle varies between individuals but stays consistent for many within 24 to 38 days.

Bleeding itself usually lasts 2 to 7 days, heaviest in the first couple of days.

In the first few years after menstruation starts (around ages 9-15), cycles often irregular, lengthening to every 4-5 weeks by 2-3 years in.

Factors Affecting Frequency

Stress, weight changes, illness, hormonal birth control, or conditions like fibroids can make periods come more often (under 21 days) or less (over 35 days).

Perimenopause shortens cycles for some, while teens and early years see natural spacing.

Tracking via apps helps spot your pattern—apps like Clue note 24-38 days as typical.

When It's Irregular

Real experiences vary: Forum threads like Reddit's AskWomen show many report 28-day clocks, but low-karma posts get flagged—highlighting how personal stories mix with moderation.

If periods hit sooner than 21 days regularly, skip more than 35, last over a week, or involve heavy clots/soaking hourly, see a doctor—it could signal issues like anovulation.

NHS advises: Common range 21-35 days, but consult if absent 3+ months.

Scenario| Typical Frequency| When to Worry
---|---|---
Average adult| Every 28 days 1| <21 or >35 days ongoing 1
Teens/early years| Every 4-5 weeks after 2-3 years 9| No period 3 months 1
Perimenopause| Shorter/irregular 1| Heavy bleeding hourly 1

Tracking Tips

  1. Mark first bleed day monthly.
  2. Note length/flow changes.
  3. Use free NHS/Mayo tools online.

TL;DR: Periods come every 21-35 days normally (avg. 28); track yours and see a doc for outliers.

Information gathered from public forums or data available on the internet and portrayed here.