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Gestational calculator and EDD

Calculate estimated gestational age and EDD by LMP, known EDD or previous ultrasound, with clear limits of obstetric evaluation.

Calculator

In addition to Last Menstrual Period, the calculator allows switching to Estimated Due Date or Previous Ultrasound when this information has already been defined during follow-up.

Reference date: today, in the browser. The result shows estimated EDD and estimated gestational age, but does not replace obstetric evaluation.

The typed data stays in your browser and is not sent to the server.

How to interpret

This calculator estimates the gestational age on the reference date and the estimated EDD from the most reliable information available: LMP, known EDD, or previous ultrasound. The result is an initial calculation, useful for conversation and organization, but does not replace obstetric evaluation.

Frequently asked questions

Public support sources

The sources below support the general logic of LMP, 40 weeks/280 days, EDD uncertainty, and the importance of early ultrasound when indicated.

• ACOG/SMFM: Methods for Estimating the Due Date
• Johns Hopkins Medicine: Calculating a Due Date
• NHS: Due date calculator
• Merck Manual: Physiology of Pregnancy
• Merck Manual: Gestational Age
• Public ultrasound hub
• Ultrasound preparation
• Ultrasound Academy
• System for clinics
• Editorial policy
• Official contact

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