FERTILIZATION TIMING

Conception Date Calculator

Find out when conception most likely occurred and the sexual intercourse window that led to pregnancy based on your due date or last period.

Probable Conception Timing Biological Estimate

Most Probable Conception Date

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Intercourse Window: —

Biological Lifespan

12–24 Hours

Oocyte viability after ovulation

Sperm Viability Window

Up to 5 Days

In fertile cervical mucus

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Biological Clarification: Conception occurs within hours of ovulation. However, sexual intercourse leading to pregnancy could have occurred up to 5 days prior to ovulation, as sperm can survive in the reproductive tract awaiting the release of the egg.

The Physiology of Conception

Human conception requires the precise meeting of a viable oocyte and capacitated sperm within the ampulla of the fallopian tube. While the window for fertilization is biologically narrow—an egg degenerates within 12 to 24 hours of ovulatory rupture—the window for coitus is much broader.

Understanding the 266-Day Gestational Interval

From the moment of true fertilization to the birth of a full-term infant, embryonic and fetal gestation averages 266 days (38 weeks). Because most women do not know their precise hour of ovulation, clinical medicine calculates gestational age from the first day of the last menstrual period (adding 14 days, for a 280-day total).