Baby Weeks Calculator



Calculating the gestational age of a pregnancy is crucial for monitoring fetal development. The Baby Weeks Calculator simplifies this process, providing an easy-to-use tool for determining the number of weeks into a pregnancy. In this article, we’ll guide you through using the calculator, explain the underlying formula, provide examples, address frequently asked questions, and conclude with the importance of accurate gestational age tracking.

How to Use

Using the Baby Weeks Calculator is straightforward. Enter the date of the first day of the last menstrual period (LMP) in the input field. Click the “Calculate” button, and the tool will display the gestational age in weeks.


The calculator employs the Naegele’s Rule, a widely accepted method for estimating the due date of a pregnancy. The formula is as follows:


  • EDD is the estimated due date.
  • LMP is the first day of the last menstrual period.


Let’s say the LMP is January 1, 2023. Applying the formula:

The result would be the estimated due date.


Q: Is the Baby Weeks Calculator accurate?

A: The calculator uses a widely accepted formula, providing a good estimate. However, for precise results, consult with a healthcare professional.

Q: Can I use the calculator for irregular menstrual cycles?

A: The calculator assumes a regular 28-day cycle. For irregular cycles, it may not be as accurate. Consult with a healthcare provider for personalized guidance.

Q: Is gestational age the same as fetal age?

A: No, gestational age is measured from the first day of the LMP, while fetal age is measured from the date of conception.


The Baby Weeks Calculator offers a convenient way to estimate gestational age during pregnancy. While it provides a useful estimate, always consult with healthcare professionals for accurate guidance tailored to individual circumstances.

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