The Conception Calculator

Conceived on Boxing Day? Here's the Due Date

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

If conception happened on Boxing Day (December 26), the baby would be due around September 18 the following year.

Conception dateDecember 26
Estimated due dateSeptember 18
Likely due window (37–42 weeks)August 28 – October 2
Last period probably startedDecember 12

Remember that sex and conception aren't always on the same day: sperm can survive for up to five days, so a holiday celebration could lead to conception a few days later.

Check your own dates with the due date calculator.

Due Date Calculator: Estimate your due date from the first day of your last period.

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