The Conception Calculator

Due Date May 4: When Did You Conceive?

Due dates & conception. Updated . Calculated with the standard pregnancy dating method used by ACOG and the NHS.

Wondering when your May 4 baby was conceived? Using the standard 266-day rule, the answer is most likely August 11 of the previous year, give or take a few days.

Key dates for a May 4 due date

Most likely conception dateAugust 11
Likely conception windowAugust 8 – August 14
Days when sex could have led to pregnancyAugust 6 – August 12
Estimated first day of last periodJuly 28
Positive home test likely fromAugust 25 (around the missed period)
Second trimester begins (14 weeks)November 3
Third trimester begins (28 weeks)February 9
Full term begins (39 weeks)April 27

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 May 4 gives August 11.

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 August 11; 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.

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This article is general information, not medical advice. Talk to a doctor or midwife about your own pregnancy or fertility.