Ovulation Calculator

Ovulation is estimated by counting back 14 days from the *next* expected period, because the post-ovulation (luteal) phase is far more consistent than the pre-ovulation phase. The fertile window spans the five days before ovulation plus the day itself — sperm survive days; the egg, hours.

Cycles vary — stress, travel, and illness shift ovulation. Ovulation predictor kits (LH strips), basal body temperature, and cervical-mucus tracking pin the day far better than arithmetic. Irregular cycles deserve a clinician's input.