Naegele's rule
Due date = first day of last period + 280 days, adjusted for cycles longer or shorter than 28 days.
Frequently asked questions
How many babies arrive on the due date?
Only about 4–5%. Most arrive within two weeks either side.
Due Date Calculator
Estimate your baby's due date from your last period.
Your details
Estimated due date
Tue, July 13, 2027
Weeks pregnant today
4 weeks
Conception (approx.)
Tue, October 20, 2026