How to track irregular periods
If your cycle doesn't show up on a schedule, most period apps get it wrong. Here's what counts as irregular, what can cause it, and how to track it in a way that's actually useful.
What counts as an irregular period?
The NHS says the average cycle is about 28 days, but it's common to have a cycle anywhere from 21 to 35 days. Periods are considered irregular when the gap between them is less than 21 days or more than 35 days, or when the length keeps changing a lot.
Irregular periods are especially common in the first years after periods start and in the years before menopause.
Common causes
- Puberty and perimenopause (usually between 45 and 55)
- Hormonal contraception, like the progestogen-only pill, injection, or IUS
- Big changes in weight, stress, or very intense exercise
- Conditions like PMOS (formerly called PCOS) and thyroid problems
When to see a doctor
The NHS suggests seeing a GP if your periods are irregular, if they last longer than 7 days, if you bleed between periods, or if irregular periods come with symptoms like weight gain, tiredness, facial hair growth, or dry or oily skin. It also suggests seeing a GP if you've missed 3 or more periods in a row.
How to track an irregular cycle
- Log the day each period starts and ends. Cycle length is counted from one start to the next, so start dates matter most.
- Log spotting separately from your period, so it doesn't throw off your cycle lengths.
- Note symptoms and flow, including very heavy days and clots, so you can show a doctor what's really happening.
- Look at the range, not one date. With irregular cycles, an honest window is more useful than a confident guess.
How Rue helps with irregular cycles
Rue never assumes 28 days. It learns from your own history and shows your next period as a range that gets wider when your cycles vary. A couple of days after the predicted date it gently asks whether your period has started, and later whether it ended, so your history stays accurate even if you forget to log.
When it's time to see a doctor, Rue's free doctor visit summary lists your cycle lengths, period lengths, and anything worth mentioning, like long gaps or very heavy periods, each linked to NHS guidance. You can also export everything as a spreadsheet for free.
No account, no ads, no data sold. Your data stays on your devices and your own private iCloud.
Download on the App StoreCommon questions
It can give a useful range, but not an exact date. Rue predicts from your own history and widens the window when your cycles vary, so it doesn't claim more certainty than it has.
The NHS describes periods as irregular when the gap between them is less than 21 days or more than 35 days, or when the length keeps changing. It suggests seeing a GP if you've missed 3 or more periods in a row.
Irregular periods are common, especially in the first years after periods start and in the years before menopause. They can also be caused by stress, weight changes, contraception, or conditions like PMOS and thyroid problems, so it's worth talking to a GP if you're unsure.
Yes. Period tracking, predictions, check-ins, the calendar, the doctor visit summary, and spreadsheet export are free. Rue+ is optional.
Sources
NHS: Irregular periods
NHS: Periods
NHS: Stopped or missed periods
Office on Women's Health: Your menstrual cycle
Rue is not a medical device and doesn't diagnose conditions. This page is general information, not medical advice. If you're worried about your periods, talk to a doctor.
More: irregular periods · PCOS · perimenopause · support · privacy