Ovulation Calculator
Estimate your most fertile days.
Enter the first day of your last menstrual period
Ovulation is when a mature egg is released from the ovary, making it available for fertilization. This typically occurs once per menstrual cycle, about 14 days before your next period begins.
The egg survives only 12-24 hours after release, but sperm can live in the reproductive tract for up to 5 days. This is why the "fertile window" spans about 6 days—5 days before ovulation plus the day of ovulation itself.
Calendar Method
Track your cycles to predict ovulation. Works best for regular cycles but can be less accurate month-to-month.
Basal Body Temperature (BBT)
Your temperature rises slightly (0.4-1.0°F) after ovulation. Track daily to identify patterns. Confirms ovulation has occurred.
Ovulation Predictor Kits (OPKs)
Detect the LH surge that occurs 24-48 hours before ovulation. More precise than calendar tracking for timing intercourse.
Cervical Mucus
Near ovulation, cervical mucus becomes clear, stretchy, and slippery (like egg whites)—optimal for sperm transport.
Many factors can influence your fertility:
- Age: Fertility declines after age 35, more sharply after 40
- Weight: Both underweight and overweight can affect ovulation
- Stress: High stress can disrupt hormone balance and ovulation
- Lifestyle: Smoking, excessive alcohol, and poor diet can reduce fertility
- Medical conditions: PCOS, endometriosis, thyroid disorders can affect cycles
If you've been trying to conceive for over a year (or 6 months if over 35), consult a fertility specialist.
Frequently Asked Questions
The highest chance of conception is during the 'fertile window'—the 5 days before ovulation and the day of ovulation itself. The peak days are the day before and day of ovulation, when sperm can meet the released egg.
This calculator estimates ovulation based on average cycle patterns. It works best for women with regular cycles. For more accuracy, combine with other methods like basal body temperature tracking, ovulation predictor kits (OPKs), or cervical mucus monitoring.
If your cycle length varies significantly (more than 7 days), predictions become less reliable. Consider tracking your cycle for several months to find your average, or use ovulation predictor kits for more accurate results.
Ovulation itself is brief—the egg is released and viable for only 12-24 hours. However, sperm can survive in the reproductive tract for up to 5 days, which is why the fertile window is several days long.
Common signs include: increased cervical mucus (clear, stretchy, egg-white consistency), slight rise in basal body temperature, mild pelvic pain or cramping (mittelschmerz), increased libido, and breast tenderness.
While rare, it's possible if you have a short cycle. Sperm can survive up to 5 days, so if you ovulate shortly after your period, the sperm could still be viable. Use protection if you're not trying to conceive.
Important Notice
This calculator provides estimates based on average cycle patterns and should not be used as a contraceptive method. Actual ovulation timing can vary. For family planning advice, consult with a healthcare provider. If you have irregular cycles or fertility concerns, seek professional medical guidance.