Due Date August 20: When Did You Conceive?
Wondering when your August 20 baby was conceived? Using the standard 266-day rule, the answer is most likely November 27 of the previous year, give or take a few days.
Key dates for a August 20 due date
| Most likely conception date | November 27 |
|---|---|
| Likely conception window | November 24 – November 30 |
| Days when sex could have led to pregnancy | November 22 – November 28 |
| Estimated first day of last period | November 13 |
| Positive home test likely from | December 11 (around the missed period) |
| Second trimester begins (14 weeks) | February 19 |
| Third trimester begins (28 weeks) | May 28 |
| Full term begins (39 weeks) | August 13 |
How the conception date is calculated
Due dates are normally counted as 280 days (40 weeks) from the first day of the last menstrual period. In a typical 28-day cycle, ovulation and conception happen about two weeks after that period starts, so conception sits roughly 266 days before the due date. Subtracting 266 days from August 20 gives November 27.
Sperm can survive in the reproductive tract for up to five days, while an egg lives for about 12 to 24 hours after ovulation. That means sex several days before ovulation can still lead to pregnancy.
How certain is this date?
Remember that a due date is only the midpoint of a range. Ovulation timing varies from cycle to cycle, so the true conception day can sit a few days away from the estimate.
If your cycles are usually longer than 28 days, conception probably happened a little later than November 27; with shorter cycles, a little earlier. A cycle that is 32 days long, for example, shifts the likely date about four days later.
Check your own dates
Enter your exact due date in the conception date calculator to see these results with weekdays and the correct year, or start from your last period with the last-period conception calculator.
Conception Date Calculator: Find the most likely conception date from your due date.
Open the calculatorThis article is general information, not medical advice. Talk to a doctor or midwife about your own pregnancy or fertility.