Read more: FAQs & context
Clinical practice
Real-world EDD may still be revised after CRL measurement. Use this page for learning, not for booking induction without medical review.
Classic EDD
Traditional EDD: add 1 year, subtract 3 months, add 7 days to LMP — shown next to the 280-day total.
Purpose, how to use it, and benefits — the interactive tool is in the card above whenever you want to jump back.
Naegele’s rule is the classic teaching formula: add one year, subtract three months, add seven days to the LMP. This page shows that side by side with the simpler “+280 days” result.
Enter your LMP and tap Apply. If both dates match or differ by a day, you will see why month lengths create tiny differences.
Students, doulas, and curious parents understand how textbook rules connect to calendar arithmetic.
Real-world EDD may still be revised after CRL measurement. Use this page for learning, not for booking induction without medical review.