Pregnancy Due Date Calculator.

Locate conception windows and due dates using standard gestational cycle adjustments.

Input Parameters

First Day of Last Period

Manual Keyboard Input / Calendar

Dropdown Selectors

Cycle Duration

days

Comments & Feedback.

Documentation

User manual & function guide.

Detailed manual explaining every function, input parameter, and operational example for the Pregnancy Due Date Calculator.

Last Period & Cycle

Function

LMP date and average cycle length in days.

Example Operation LMP = 2026-01-01, Cycle = 28 days

Naegele's Rule Calculation

Function

Calculates adjusted due date.

Example Operation 2026-01-01 + 280 days = October 8, 2026

Frequently asked questions.

How is the due date calculated?

Due date is calculated using Naegele's rule: add 280 days to the first day of your last menstrual period, then adjust for cycle length variations from the standard 28-day cycle.

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