Pregnancy Due Date Calculator

Due date from last menstrual period (Naegele's rule) plus current week and trimester.

First day of last period:

How to use

Enter the first day of the last menstrual period, then click Calculate.

How accurate is Naegele's rule?

It estimates ~40 weeks from LMP; only ~5% arrive exactly on the due date. Ultrasound dating is more precise.

Is this medical advice?

No — confirm everything with your healthcare provider. This is a planning estimate.

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