Gestational Age Calculator

First Day of Last Period (LMP)

In modern obstetrics, gestational age is measured from the first day of your last menstrual period (LMP). While biologically the first two weeks represent the pre-conception phase, this standardized measurement is the global protocol for tracking fetal development. For early arrivals, our Adjusted Age Tool becomes essential for post-natal tracking.

Maintaining precise knowledge of your weeks and days is vital for timing clinical screenings and ultrasounds. Beyond immediate tracking, you can use our engine to project future milestones such as your child's School Enrollment Year or their very first 6-month anniversary.

Understanding development involves both the pre-natal phase and the journey beyond. For a live look at time passing, explore our Age in Seconds Clock.

Pregnancy Timing Questions

Why is pregnancy measured from the last period?

Because the exact moment of conception is rarely identifiable, medical science uses the LMP as a reliable anchor point. For more definitions, explore our Age Hub.

What defines a "Full Term" pregnancy?

A pregnancy is considered full term at 39 weeks. If birth occurs before 37 weeks, we recommend utilizing the Adjusted Age Tool for accurate developmental monitoring.

How many total days is a human pregnancy?

The average duration is 280 days. You can track this specific countdown using our Countdown Engine logic.

When will my baby start school?

Use our School Age Calculator to predict future enrollment dates based on their projected birth year.

Infant Development Tools

Adjusted (Preemie) Age School Start Age Half Birthday Age Calculator