Calculate Due Date

Calculate your estimated due date based on your last period.

Last Period Start Date

Cycle Length (days)

Estimated Due Date

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Current Progress

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The Methodology

Naegele's Rule (LMP + 280 days)

This tool uses the verified professional formula shown above. We cite our sources so you can trust every result.

How it works

Naegele's rule is the standard method used by healthcare providers. It assumes a 28-day cycle and adds 40 weeks to the start of your last menstrual period.