Gestational Age Calculator

Calculate gestational age, pregnancy weeks, and estimated due date from last menstrual period or conception date.

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Worked Example & Common Values

Below is a sample worked calculation demonstrating how Gestational Age Calculator processes input data instantly inside your browser.

Sample Input Birth date: Jan 15, 1995, Target date: Oct 20, 2023

Computed Result Chronological Age: 28 Years, 9 Months, 5 Days (10,505 days elapsed)

Execution Mode Client-Side In-Browser JS

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About This Tool

This gestational age calculator helps you determine how many weeks and days pregnant you are based on your last menstrual period (LMP) or conception date. It provides accurate results including the current gestational age in weeks and days, the pregnancy trimester, and the estimated due date. The tool is designed for healthcare professionals, expectant parents, and anyone needing to track pregnancy progress with a simple, intuitive interface.

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How to Use

Select either 'Last Menstrual Period (LMP)' or 'Conception Date' as your input method.
Enter the date using the date picker or manual input.
Click the 'Calculate Gestational Age' button.
View the results including weeks, days, trimester, and due date in the result section below.

Frequently Asked Questions

Find Quick Answers

What is gestational age?

Gestational age is the duration of pregnancy measured from the first day of the last menstrual period (LMP) to the current date, typically expressed in weeks and days.

How accurate is this calculator?

This calculator uses standard medical formulas (Naegele's rule for due date) and assumes a 28-day menstrual cycle. For precise medical advice, consult a healthcare provider as individual factors may vary.

Can I use conception date instead of LMP?

Yes, you can select 'Conception Date' as the input method. The calculator will add 266 days (38 weeks) to estimate the due date and calculate gestational age accordingly.

What is Naegele's rule?

Naegele's rule is a standard method to estimate due date: add 7 days to the first day of the last menstrual period, then subtract 3 months. This calculator applies it when using LMP.

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