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Date & Time
Due Date
Estimate a pregnancy due date using Naegele's rule — 280 days from the first day of the last menstrual period. This is a common estimate, not medical advice.
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Worked example
Estimated due: 2027-01-06
Inputs
- Last period
2026-04-01
Frequently asked
How is the due date calculated?
By adding 280 days (40 weeks) to the last-period date.
How accurate is it?
It's a standard estimate; only about 1 in 20 births lands exactly on the predicted day.