Due Date Calculator (by Conception Date)
Calculate your delivery date based on the exact date of conception. High-precision tool for fertility tracking and ovulation confirmation.
About
Standard pregnancy calculations usually start from the Last Menstrual Period (LMP) because the exact date of conception is rarely known in the general population. However, for individuals tracking basal body temperature (BBT) or confirming ovulation via medical testing, calculating from the Date of Conception offers significantly higher accuracy.
This method bypasses the follicular phase variability entirely. While the LMP method assumes a 14-day pre-ovulation phase, actual follicular phases can range from 10 to 21 days. By anchoring the timeline to the biological start of the embryo (fertilization), the "280-day rule" is replaced by the physiological gestation period of 266 days.
Formulas
The calculation is a direct addition of the standard human gestation period to the confirmed conception date:
This is mathematically equivalent to:
Reference Data
| Event | Timeline (Days Post-Conception) | Reference |
|---|---|---|
| Implantation | 6 - 12 Days | Blastocyst attaches to uterine wall. |
| Missed Period | 14 Days | Approximate. hCG levels become detectable. |
| Fetal Heartbeat | 22 - 25 Days | Tubular heart begins beating. |
| Anatomy Scan | 126 - 140 Days | 18-20 Weeks gestation. |
| Estimated Delivery | 266 Days | 38 Weeks post-conception (40w LMP). |