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About the Due Date Calculator
This calculator estimates your baby's due date from the first day of your last menstrual period or from your conception date. The output includes an estimated delivery date, a trimester breakdown, and key pregnancy milestones such as the end of the first trimester.
For period-based estimates, the calculator applies Naegele's rule, which adds 280 days, or 40 weeks, to the first day of your last period. Conception-based estimates add 266 days to the conception date. You only need one accurate date to start. Enter the first day of your last period rather than the day it ended for the best result. The result is an estimate, so consider confirming dates with a healthcare professional.
- Pick last menstrual period or conception date as your starting point.
- Enter that date in the input field.
- Click calculate to see your due date, trimesters, and milestones.