The Conception Calculator

When Did I Conceive if My Due Date Is June 5?

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

Wondering when your June 5 baby was conceived? Using the standard 266-day rule, the answer is most likely September 12 of the previous year, give or take a few days.

Key dates for a June 5 due date

Most likely conception dateSeptember 12
Likely conception windowSeptember 9 – September 15
Days when sex could have led to pregnancySeptember 7 – September 13
Estimated first day of last periodAugust 29
Positive home test likely fromSeptember 26 (around the missed period)
Second trimester begins (14 weeks)December 5
Third trimester begins (28 weeks)March 13
Full term begins (39 weeks)May 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 June 5 gives September 12.

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?

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 September 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.