Due Date Calculator
The Due Date Calculator estimates your baby's expected delivery date from either the first day of your last menstrual period or your estimated conception date.
Estimated Due Date
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Weeks Remaining (from today)--
How each method works
From your last menstrual period (LMP), pregnancy is estimated to last 280 days (40 weeks). From a known conception date, it's estimated at 266 days (38 weeks), since conception typically occurs about two weeks after the start of the last period.
Due Date (from LMP) = LMP + 280 days
Due Date (from Conception) = Conception Date + 266 days
Example: A last period starting January 1st gives an estimated due date around October 8th. A conception date of January 15th gives roughly the same estimated due date.
Accuracy
Only about 5% of babies are born exactly on their estimated due date — most arrive within two weeks before or after. This is a statistical estimate, not a guarantee; your healthcare provider may adjust it based on ultrasound measurements. See also our Pregnancy Calculator and Conception Calculator.