Conception occurs when a sperm fertilizes an egg, which typically happens in the fallopian tube. For most women with regular cycles, ovulation (the release of an egg) occurs approximately 14 days before the start of the next menstrual period.

The most fertile period (when conception is most likely to occur) includes the day of ovulation and the five days before it. This is because sperm can survive in a woman's reproductive tract for up to five days, while an egg is typically viable for only 12-24 hours after ovulation.

This calculator provides estimates based on average cycle patterns. Every woman's body is different, and many factors can affect ovulation timing. For the most accurate tracking, consider using additional methods such as basal body temperature charting, ovulation predictor kits, or fertility monitoring apps.

If you're trying to conceive, having intercourse every 1-2 days during your fertile window maximizes your chances. If you're trying to avoid pregnancy, remember that this calculator provides estimates only and should not be used as a reliable form of birth control.