The Conception Calculator

When Did I Conceive if My Due Date Is May 6?

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

A due date of May 6 points back to a conception date of about August 13 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 May 6 due date

Most likely conception dateAugust 13
Likely conception windowAugust 10 – August 16
Days when sex could have led to pregnancyAugust 8 – August 14
Estimated first day of last periodJuly 30
Positive home test likely fromAugust 27 (around the missed period)
Second trimester begins (14 weeks)November 5
Third trimester begins (28 weeks)February 11
Full term begins (39 weeks)April 29

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 6 gives August 13.

Conception happens when sperm meets the egg, usually within a day of ovulation. Since sperm may wait up to five days for an egg to be released, the window for sex that could have caused the pregnancy is wider than a single day.

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 August 13; 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.