Ovulation calculator

We estimate the next period start from your last period date and average cycle length, then place ovulation about 14 days before that start. A fertile window is shown around that midpoint.

Real ovulation can move several days month to month even with a stable average length.

Treat the fertile window as a rough map, not a guarantee of conception timing.

Sperm can survive several days in the reproductive tract; eggs have a shorter viable window. Apps cannot replace hormone testing or ultrasound when timing matters medically.

If cycles vary widely, an average length may hide late or early ovulation—LH strips or BBT logs help some users.

Stress, illness, travel, and medications can shift ovulation without obvious cycle-length changes.

For contraception decisions, use methods with verified effectiveness and professional counseling—not calendar estimates alone.

Not for diagnosing infertility or hormonal disorders.

If you have irregular cycles, pelvic pain, or are on fertility treatment, follow your specialist’s protocol.