Due Date November 15: When Did You Conceive?
Counting back from a November 15 due date puts the most likely day of conception at February 22. That's an estimate, so we've also included the window of days around it.
Key dates for a November 15 due date
| Most likely conception date | February 22 |
|---|---|
| Likely conception window | February 19 – February 25 |
| Days when sex could have led to pregnancy | February 17 – February 23 |
| Estimated first day of last period | February 8 |
| Positive home test likely from | March 8 (around the missed period) |
| Second trimester begins (14 weeks) | May 17 |
| Third trimester begins (28 weeks) | August 23 |
| Full term begins (39 weeks) | November 8 |
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 November 15 gives February 22.
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?
Due dates set from an early ultrasound are usually more accurate than those set from a period date alone, so if your provider changed your due date after a scan, use the newer one here.
If your cycles are usually longer than 28 days, conception probably happened a little later than February 22; 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.