Period & Cycle Tracker
Keeping track of your cycle helps you know when your next period is due, plan around it, and spot when something changes. Enter the first day of your last period and your average cycle length, and we’ll predict your upcoming periods, your fertile window, and your estimated ovulation day — instantly and privately, with no sign-up.
How period tracking works
A menstrual cycle is counted from the first day of one period to the first day of the next. By projecting forward from your last period using your typical cycle length, you can anticipate the months ahead. Because ovulation usually happens about two weeks before your next period, the same dates also reveal your most fertile days.
Related tools
- Ovulation Calculator — find your most fertile days if you’re trying to conceive.
- Understanding your menstrual cycle — the four phases explained.
- Pregnancy Tracker — follow week by week if you conceive.
Common questions
How does the period tracker predict my next period?
From the first day of your last period and your average cycle length, it counts forward one full cycle to estimate the start of your next period, and repeats that to project the months ahead. The more accurate your cycle length, the better the prediction.
What is a normal cycle length?
Most cycles run between 21 and 35 days, measured from the first day of one period to the first day of the next. Cycles can vary by a few days month to month, which is completely normal. If yours are very irregular, it is worth mentioning to your doctor.
Can a period tracker tell me my fertile days?
Yes — because ovulation is tied to your cycle, the same dates let us estimate your fertile window and most fertile days. If you are trying to conceive, see the ovulation calculator; if you want to understand your cycle phases, see our menstrual cycle guide.
Predictions are estimates based on a regular cycle and are not medical advice. For irregular cycles or concerns about your period, please speak with your doctor.