Your next period should start on
Your next 6 periods
| Starts | Ends |
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Predictions assume regular cycles. Do not use this calculator as a method of contraception.
How is my next period calculated?
Your cycle starts on the first day of bleeding. The calculator adds your average cycle length to that date to find the start of each following period, then adds your usual period length to estimate when it will end.
What is a normal cycle?
For adults, a cycle anywhere from 21 to 35 days is considered normal, and a period usually lasts from 2 to 7 days. It is common for cycle length to vary by a few days from month to month. For teenagers, cycles can be longer and less regular in the first few years.
When to see a doctor about your periods
- Your periods stop for more than 3 months and you are not pregnant
- Your cycle is shorter than 21 days or longer than 35 days
- Bleeding lasts more than 7 days or is very heavy
- You bleed between periods, after sex or after menopause
- Period pain stops you from doing everyday things
Frequently asked questions
My period is late. Could I be pregnant?
It is possible. Home pregnancy tests are most reliable from the first day of a missed period. Stress, illness, weight change and some medicines can also delay a period.
How do I find my average cycle length?
Count the days from the first day of one period to the day before the next one starts. Do this for 3 to 6 months and take the average.
Why are my periods irregular?
Common reasons include stress, big changes in weight, intense exercise, PCOS, thyroid problems and the years around puberty and menopause. A doctor can help if you are worried.
Is my information saved?
No. The calculation runs in your browser and nothing is stored.