◑ HEALTH Updated July 25, 2026

Pregnancy Due Date Calculator

Due date, trimester, and weeks pregnant.

First day of last period
Cycle length (days)
Result
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How it works

The estimate uses Naegele's rule: 280 days from the first day of the last menstrual period, adjusted for cycle length.

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Frequently asked questions

How accurate is a due date?

Only about 4 percent of babies arrive on the exact date; most births fall within two weeks either side.

Is this a substitute for a scan?

No. A dating ultrasound in the first trimester is the most reliable estimate.

Comments

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