A tracker for periods that don't keep a schedule
If your period arrives early one month and late the next, a single predicted date isn't much help. LunWise shows how confident each prediction is, learns from your recent cycles and tells you when a pattern is worth a check-up.
How LunWise helps
- Recent cycles count most, so predictions adjust quickly when your cycle shifts.
- Every prediction comes with a date range and a high, medium or low confidence label.
- An accuracy scorecard shows how close LunWise's predictions have been for you.
- Confirm ovulation with LH tests or temperature to tighten your next prediction.
- Plain-language flags when your cycles fall outside clinical guidelines.
What counts as an irregular period
Clinical guidelines from FIGO describe typical cycles as 24 to 38 days long, with bleeding lasting up to 8 days. Cycles are considered regular when the difference between your shortest and longest cycle is about 7 to 9 days or less, depending on age.
Variation is more common than many people think. In a study of more than 600,000 cycles, only about 13% were exactly 28 days long, and the average was 29.3 days.
Common reasons cycles become irregular
- Stress, illness, travel or big changes in sleep
- Changes in weight or exercise
- Polycystic ovary syndrome (PCOS) or thyroid conditions
- Starting or stopping hormonal birth control
- Pregnancy, breastfeeding and the months after
- Perimenopause
An occasional off cycle is common. Repeated patterns, like cycles shorter than 24 days or longer than 38, are worth discussing with a clinician, and LunWise points them out when they appear in your history.
Questions and answers
How irregular is too irregular?
By FIGO guidelines, cycles are irregular when your shortest and longest cycles differ by more than about 7 to 9 days. Cycles regularly shorter than 24 days or longer than 38 days are also outside the typical range.
Can a period tracker help with irregular periods?
Yes. A record of your actual cycles shows patterns that are easy to miss and gives a clinician real data. LunWise also shows how reliable each prediction is, so you know how much to plan around it.
Should I see a doctor about irregular periods?
If your cycles are often outside 24–38 days, vary a lot, or you go 90 days without a period, it's worth checking in with a clinician. If there's any chance you could be pregnant, a test is a good first step.
Sources
Last updated October 11, 2026. This page is for general information and isn't medical advice.