The Conception Calculator

Due Date April 4: When Did You Conceive?

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

A due date of April 4 points back to a conception date of about July 12 of the previous year. Below you'll find the full set of dates that go with it, from your estimated last period to the start of each trimester.

Key dates for a April 4 due date

Most likely conception dateJuly 12
Likely conception windowJuly 9 – July 15
Days when sex could have led to pregnancyJuly 7 – July 13
Estimated first day of last periodJune 28
Positive home test likely fromJuly 26 (around the missed period)
Second trimester begins (14 weeks)October 4
Third trimester begins (28 weeks)January 10
Full term begins (39 weeks)March 28

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 April 4 gives July 12.

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?

A due date is a planning estimate rather than a promise. Most babies arrive within two weeks either side of it, which is why any conception date calculated from it is a best guess.

If your cycles are usually longer than 28 days, conception probably happened a little later than July 12; 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.