Here are four different methods of calculation that both midwives and doctors use. While no method is 100% correct, these are methods to show estimated dates of delivery.

280-day method.

Enter the date of the first day of your last period.

If this is your first pregnancy, check here:
Month:	Day:	Year:		Your due date is:
	,

(The 280-day method calculates the baby's due date to be 280 days from the first day of your last period (LMP).)

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Nagel's method.

Enter the first day of your last period.

Month:	Day:	Year:		Your due date is:
	,

(Nagel's method calculates the baby's due date according to the following formula: LMP + 7 days - 3 months + 1 year.)

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Wood's method.

Enter the first day of your last period and the deviation + or - from a 28 day cycle.

If this is your first pregnancy, check here:
Month:	Day:	Year:	Deviation:		Your due date is:
	,

(Wood's method calculates the baby's due date according to the following formula: LMP + 1 year - 2 months, 14 days +/- deviation from the standard 28-day cycle.)

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Quickening method (from first sensation of movement).

Enter the date you first felt the baby move.

Month:	Day:	Year:		Your due date is:
	,

(The quickening method calculates the baby's due date to be 5 months from the date the baby first moved.)