Due Date Calculator
Typical range: 21—35 days. Default is 28.
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Estimated Due Date
Current Week—
Trimester—
Weeks Remaining—
Conception Date (estimated)—
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How to Use
Select whether to calculate based on your LMP or conception date. If using LMP, enter the first day of your last period and your average cycle length. The calculator uses Naegele's rule: 280 days from LMP, adjusted for cycle length.
Frequently Asked Questions
Only about 5% of babies arrive on their exact due date. The due date is an estimate — most babies arrive between 38 and 42 weeks.
Naegele's rule is the standard method for estimating due dates. It adds 280 days (40 weeks) to the first day of your LMP, then adjusts for cycle length.
First trimester: weeks 1-12. Second trimester: weeks 13-27. Third trimester: week 28 until birth.
Yes. If your cycle is longer than 28 days, ovulation happens later, so the due date shifts forward. If shorter, it shifts backward.