Ovulation Calculator: Understanding Your Fertile Window
Knowing when you ovulate is essential for both achieving and avoiding pregnancy. Our ovulation calculator estimates your fertile window—the days when conception is most likely—based on your cycle length and last menstrual period. The interactive calendar view shows multiple months of predictions at a glance.
Ovulation typically occurs about 14 days before your next period, regardless of cycle length. If you have a 28-day cycle, that's around day 14. For a 32-day cycle, it's around day 18. The fertile window includes the 5 days before ovulation (sperm can survive that long) plus the day of ovulation itself. For pregnancy planning, see our Pregnancy Due Date Calculator.
Understanding Your Cycle
Menstrual Phase: Days 1-5 typically, when bleeding occurs. Follicular Phase: After menstruation until ovulation, when eggs mature. Ovulation: Release of a mature egg, typically mid-cycle. Luteal Phase: After ovulation until next period, typically 14 days.
Signs of Ovulation
Cervical mucus changes: Becomes clear, stretchy, and egg-white-like. Basal body temperature: Rises slightly (0.5-1°F) after ovulation. Mild cramping: Mittelschmerz, or ovulation pain, on one side. Increased libido: Natural fertility signal.
FAQ
How accurate is this calculator?
It's based on averages and works best for regular cycles. Factors like stress, illness, and hormonal changes can shift ovulation. For higher accuracy, combine with ovulation predictor kits (OPKs) or basal body temperature tracking.
What if my cycles are irregular?
Use your average cycle length. For highly irregular cycles, calculator predictions are less reliable—consider consulting a healthcare provider and using physical ovulation signs.