CalculatorsPregnancy tracking

Pregnancy Weeks to Months Calculator

Translate gestational weeks and days into an easy month-style summary and trimester.

Your details

Enter only the information needed for this estimate.

Use the completed week number from your care record. (weeks)

For example, enter 3 for a gestational age written as 18 weeks + 3 days. (days)

Calculator entries stay in this browser session to produce this result. This tool does not save them in browser storage.

Complete the fields and select “Convert weeks to months” to see your estimate.

Why pregnancy uses weeks

Gestational age is usually counted from the first day of the last menstrual period, which is about two weeks before conception in a typical cycle. Weeks and days provide a consistent timeline for appointments, scans, and milestones.

Month labels are convenient in conversation, but different charts group the boundary weeks differently. Keep using your gestational week when precision matters.

Understanding trimesters

Pregnancy is commonly divided into three trimesters. A trimester label describes a broad stage and does not change the due date or replace the gestational age in your maternity record.

Limits of this estimate

  • The month result is an approximation, not an alternative dating method.
  • This converter does not calculate gestational age from a period, transfer, or ultrasound date.
  • If your care team revised your pregnancy dating, use the gestational age in the updated record.

Common questions

How should I use this estimate?

Use it as a planning starting point, then compare it with your own experience and any guidance from a qualified health professional.

Is this medical advice?

This converter is for general education and planning. It does not date a pregnancy, provide medical advice, or replace the gestational age and due date recorded by your care team.

What happens to what I enter?

The calculator uses the values in your current browser session to produce the result. It does not save them in browser storage.