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Calculating a Due Date

How to calculate a due date:

A typical pregnancy lasts, on average, 280 days, or 40 weeks - starting with the first day of the last normal menstrual period (LMP) as day 1. An estimated due date (EDD) can be calculated by following steps 1 through 3:

  1. Determine the first day of your last menstrual period.
  2. Count back three calendar months from that date.
  3. Add one year and seven days to that date.

For example: Your last menstrual period began on September 9, 2003. Counting back three calendar months would be June 9, 2003. Adding one year and seven days would bring you to June 16, 2004, as your estimated due date (EDD).

This three-step method is referred to as Naegele's Rule and is based on a normal 28-day menstrual cycle. Therefore, dates may have to be adjusted for longer or shorter menstrual cycles. However, even with adjustments made, less than 10 percent of women actually give birth on their calculated due dates. Delivery two weeks before or after the estimated due date is still considered normal.

You may also estimate your delivery date by using the steps 1 and 2 and the chart below:

  1. Find the first day of your last menstrual period, located before the colon in the lists below.
  2. Look at the date after the colon. That is your estimated date of delivery.
Jan 1:Oct 8 May 1:Feb 5 Sep 1:Jun 8
Jan 2:Oct 9 May 2:Feb 6 Sep 2:Jun 9
Jan 3:Oct 10 May 3:Feb 7 Sep 3:Jun 10
Jan 4:Oct 11 May 4:Feb 8 Sep 4:Jun 11
Jan 5:Oct 12 May 5:Feb 9 Sep 5:Jun 12
Jan 6:Oct 13 May 6:Feb 10 Sep 6:Jun 13
Jan 7:Oct 14 May 7:Feb 11 Sep 7:Jun 14
Jan 8:Oct 15 May 8:Feb 12 Sep 8:Jun 15
Jan 9:Oct 16 May 9:Feb 13 Sep 9:Jun 16
Jan 10:Oct 17 May 10:Feb 14 Sep 10:Jun 17
Jan 11:Oct 18 May 11:Feb 15 Sep 11:Jun 18
Jan 12:Oct 19 May 12:Feb 16 Sep 12:Jun 19
Jan 13:Oct 20 May 13:Feb 17 Sep 13:Jun 20
Jan 14:Oct 21 May 14:Feb 18 Sep 14:Jun 21
Jan 15:Oct 22 May 15:Feb 19 Sep 15:Jun 22
Jan 16:Oct 23 May 16:Feb 20 Sep 16:Jun 23
Jan 17:Oct 24 May 17:Feb 21 Sep 17:Jun 24
Jan 18:Oct 25 May 18:Feb 22 Sep 18:Jun 25
Jan 19:Oct 26 May 19:Feb 23 Sep 19:Jun 26
Jan 20:Oct 27 May 20:Feb 24 Sep 20:Jun 27
Jan 21:Oct 28 May 21:Feb 25 Sep 21:Jun 28
Jan 22:Oct 29 May 22:Feb 26 Sep 22:Jun 29
Jan 23:Oct 30 May 23:Feb 27 Sep 23:Jun 30
Jan 24:Oct 31 May 24:Feb 28 Sep 24:July 1
Jan 25:Nov 1 May 25:Mar 1 Sep 25:July 2
Jan 26:Nov 2 May 26:Mar 2 Sep 26:July 3
Jan 27:Nov 3 May 27:Mar 3 Sep 27:July 4
Jan 28:Nov 4 May 28:Mar 4 Sep 28:July 5
Jan 29:Nov 5 May 29:Mar 5 Sep 29:July 6
Jan 30:Nov 6 May 30:Mar 6 Sep 30:July 7
Jan 31:Nov 7 May 31:Mar 7 Oct 1:July 8
Feb 1:Nov 8 Jun 1:Mar 8 Oct 2:July 9
Feb 2:Nov 9 Jun 2:Mar 9 Oct 3:July 10
Feb 3:Nov 10 Jun 3:Mar 10 Oct 4:July 11
Feb 4:Nov 11 Jun 4:Mar 11 Oct 5:July 12
Feb 5:Nov 12 Jun 5:Mar 12 Oct 6:July 13
Feb 6:Nov 13 Jun 6:Mar 13 Oct 7:July 14
Feb 7:Nov 14 Jun 7:Mar 14 Oct 8:July 15
Feb 8:Nov 15 Jun 8:Mar 15 Oct 9:July 16
Feb 9:Nov 16 Jun 9:Mar 16 Oct 10:July 17
Feb 10:Nov 17 Jun 10:Mar 17 Oct 11:July 18
Feb 11:Nov 18 Jun 11:Mar 18 Oct 12:July 19
Feb 12:Nov 19 Jun 12:Mar 19 Oct 13:July 20
Feb 13:Nov 20 Jun 13:Mar 20 Oct 14:July 21
Feb 14:Nov 21 Jun 14:Mar 21 Oct 15:July 22
Feb 15:Nov 22 Jun 15:Mar 22 Oct 16:July 23
Feb 16:Nov 23 Jun 16:Mar 23 Oct 17:July 24
Feb 17:Nov 24 Jun 17:Mar 24 Oct 18:July 25
Feb 18:Nov 25 Jun 18:Mar 25 Oct 19:July 26
Feb 19:Nov 26 Jun 19:Mar 26 Oct 20:July 27
Feb 20:Nov 27 Jun 20:Mar 27 Oct 21:July 28
Feb 21:Nov 28 Jun 21:Mar 28 Oct 22:July 29
Feb 22:Nov 29 Jun 22:Mar 29 Oct 23:July 30
Feb 23:Nov 30 Jun 23:Mar 30 Oct 24:July 31
Feb 24:Dec 1 Jun 24:Mar 31 Oct 25:Aug 1
Feb 25:Dec 2 Jun 25:Apr 1 Oct 26:Aug 2
Feb 26:Dec 3 Jun 26:Apr 2 Oct 27:Aug 3
Feb 27:Dec 4 Jun 27:Apr 3 Oct 28:Aug 4
Feb 28:Dec 5 Jun 28:Apr 4 Oct 29:Aug 5
Mar 1:Dec 6 Jun 29:Apr 5 Oct 30:Aug 6
Mar 2:Dec 7 Jun 30:Apr 6 Oct 31:Aug 7
Mar 3:Dec 8 July 1:Apr 7 Nov 1:Aug 8
Mar 4:Dec 9 July 2:Apr 8 Nov 2:Aug 9
Mar 5:Dec 10 July 3:Apr 9 Nov 3:Aug 10
Mar 6:Dec 11 July 4:Apr 10 Nov 4:Aug 11
Mar 7:Dec 12 July 5:Apr 11 Nov 5:Aug 12
Mar 8:Dec 13 July 6:Apr 12 Nov 6:Aug 13
Mar 9:Dec 14 July 7:Apr 13 Nov 7:Aug 14
Mar 10:Dec 15 July 8:Apr 14 Nov 8:Aug 15
Mar 11:Dec 16 July 9:Apr 15 Nov 9:Aug 16
Mar 12:Dec 17 July 10:Apr 16 Nov 10:Aug 17
Mar 13:Dec 18 July 11:Apr 17 Nov 11:Aug 18
Mar 14:Dec 19 July 12:Apr 18 Nov 12:Aug 19
Mar 15:Dec 20 July 13:Apr 19 Nov 13:Aug 20
Mar 16:Dec 21 July 14:Apr 20 Nov 14:Aug 21
Mar 17:Dec 22 July 15:Apr 21 Nov 15:Aug 22
Mar 18:Dec 23 July 16:Apr 22 Nov 16:Aug 23
Mar 19:Dec 24 July 17:Apr 23 Nov 17:Aug 24
Mar 20:Dec 25 July 18:Apr 24 Nov 18:Aug 25
Mar 21:Dec 26 July 19:Apr 25 Nov 19:Aug 26
Mar 22:Dec 27 July 20:Apr 26 Nov 20:Aug 27
Mar 23:Dec 28 July 21:Apr 27 Nov 21:Aug 28
Mar 24:Dec 29 July 22:Apr 28 Nov 22:Aug 29
Mar 25:Dec 30 July 23:Apr 29 Nov 23:Aug 30
Mar 26:Dec 31 July 24:Apr 30 Nov 24:Aug 31
Mar 27:Jan 1 July 25:May 1 Nov 25:Sep 1
Mar 28:Jan 2 July 26:May 2 Nov 26:Sep 2
Mar 9:Jan 3 July 27:May 3 Nov 27:Sep 3
Mar 30:Jan 4 July 28:May 4 Nov 28:Sep 4
Mar 31:Jan 5 July 29:May 5 Nov 29:Sep 5
Apr 1:Jan 6 July 30:May 6 Nov 30:Sep 6
Apr 2:Jan 7 July 31:May 7 Dec 1:Sep 7
Apr 3:Jan 8 Aug 1:May 8 Dec 2:Sep 8
Apr 4:Jan 9 Aug 2:May 9 Dec 3:Sep 9
Apr 5:Jan 10 Aug :May 10 Dec 4:Sep 10
Apr 6:Jan 11 Aug 4:May 11 Dec 5:Sep 11
Apr 7:Jan 12 Aug 5:May 12 Dec 6:Sep 12
Apr 8:Jan 13 Aug 6:May 13 Dec 7:Sep 13
Apr 9:Jan 14 Aug 7:May 14 Dec 8:Sep 14
Apr 10:Jan 15 Aug 8:May 15 Dec 9:Sep 15
Apr 11:Jan 16 Aug 9:May 16 Dec 10:Sep 16
Apr 12:Jan 17 Aug 10:May 17 Dec 11:Sep 17
Apr 13:Jan 18 Aug 11:May 18 Dec 12:Sep 18
Apr 14:Jan 19 Aug 12:May 19 Dec 13:Sep 19
Apr 15:Jan 20 Aug 13:May 20 Dec 14:Sep 20
Apr 16:Jan 21 Aug 14:May 21 Dec 15:Sep 21
Apr 17:Jan 22 Aug 15:May 22 Dec 16:Sep 22
Apr 18:Jan 23 Aug 16:May 23 Dec 17:Sep 23
Apr 19:Jan 24 Aug 17:May 24 Dec 18:Sep 24
Apr 20:Jan 25 Aug 18:May 25 Dec 19:Sep 25
Apr 21:Jan 26 Aug 19:May 26 Dec 20:Sep 26
Apr 22:Jan 27 Aug 20:May 27 Dec 21:Sep 27
Apr 23:Jan 28 Aug 21:May 28 Dec 22:Sep 28
Apr 24:Jan 29 Aug 22:May 29 Dec 23:Sep 29
Apr 25:Jan 30 Aug 23:May 30 Dec 24:Sep 30
Apr 26:Jan 31 Aug 24:May 31 Dec 25:Oct 1
Apr 27:Feb 1 Aug 25:Jun 1 Dec 26:Oct 2
Apr 28:Feb 2 Aug 26:Jun 2 Dec 27:Oct 3
Apr 29:Feb 3 Aug 27:Jun 3 Dec 28:Oct 4
Apr 30:Feb 4 Aug 28:Jun 4 Dec 29:Oct 5
Aug 29:Jun 5 Dec 30:Oct 6
Aug 30:Jun 6 Dec 31:Oct 7
Aug 31:Jun 7

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