FullCalculator

Due Date Calculator

From Last Menstrual Period

From Conception Date

Formula

Due Date = LMP + 280 days = Conception + 266 days

Frequently Asked Questions

How is the due date calculated?
From LMP: add 280 days (40 weeks) to the first day of your last menstrual period (Naegele's rule). From conception: add 266 days (38 weeks). Only about 5% of babies are born on their due date.

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