Cycle
Cycle & Ovulation Calculator
Calendar-based estimates for periods, ovulation, fertile windows and cycle history.
Cycle & next period
Results are calendar-based estimates. Actual ovulation and the fertile window can differ. Do not use this calculator for reliable contraception or pregnancy detection.
Result
Next estimated period
2026-01-29
Estimated ovulation dayday 14 · 2026-02-11
Estimated possible fertile window2026-02-06 – 2026-02-12
2026-01-29 – 2026-02-02
2026-02-26 – 2026-03-02
2026-03-26 – 2026-03-30
2026-04-23 – 2026-04-27
2026-05-21 – 2026-05-25
2026-06-18 – 2026-06-22
Cycle & Ovulation Calculator
Results are calendar-based estimates. Actual ovulation and the fertile window can differ. Do not use this calculator for reliable contraception or pregnancy detection.
Cycle day 1 is the first day of bleeding. Ovulation is estimated backwards from the expected cycle end; 14 days is only an editable assumption. This calendar window spans five days before through one day after.
Frequently asked questions
Is ovulation always on day 14?
No. It depends on cycle length and the luteal estimate.
Can this be contraception?
No. It does not identify safe days.
Can it detect pregnancy?
No.