Ovulation Calculator

The calendar method has about 75% accuracy with typical use. It's based on averages and assumes a 14-day luteal phase, which can vary significantly. For more accurate tracking, combine this tool with other fertility awareness methods like basal body temperature charting, ovulation predictor kits (OPKs), or cervical mucus monitoring. Ultrasound monitoring is the most accurate method but requires clinical visits.

The fertile window is the 6-day period when pregnancy is possible, ending on ovulation day. Research shows conception can occur from intercourse up to 5 days before ovulation (when sperm can survive in optimal cervical mucus) through ovulation day itself. Peak fertility occurs in the 2-3 days before ovulation. This calculator estimates your fertile window based on cycle length, but individual timing can vary.

Regular cycles vary by no more than 7 days between periods and typically range from 21-35 days. Irregular cycles have variations greater than 7 days or fall outside the normal range. Common causes include PCOS, thyroid disorders, stress, significant weight changes, or perimenopause. If your cycles are irregular, this calculator's predictions will be less accurate, and you should consult a healthcare provider.

This calculator estimates ovulation based on cycle length, but doesn't confirm it. Signs you're ovulating include: a sustained basal body temperature rise (0.2-0.5°F) after ovulation, positive ovulation predictor kit (OPK) results 24-36 hours before ovulation, egg-white cervical mucus around ovulation, and mild ovulation pain (mittelschmerz). If trying to conceive for 6+ months (age 35+) or 12+ months (under 35) without success, seek medical evaluation.

Yes, significantly. Stress, illness, travel across time zones, major weight changes, intense exercise, and certain medications can delay or prevent ovulation, making cycle predictions less reliable. The calculator assumes consistent cycles, but real-life factors often cause variations. This is why only 30% of women have predictable fertile windows during 'standard' cycle days 10-17. Track multiple signs for better accuracy.

Conditions like PCOS, thyroid disorders, endometriosis, or hormonal imbalances can make cycles unpredictable and ovulation irregular or absent. This calculator's predictions may not be accurate for these conditions. Women with PCOS may have cycles longer than 35 days or skip ovulation entirely. If you have a diagnosed condition or suspect one based on irregular cycles, work with a healthcare provider for personalized fertility tracking and treatment.