How are pregnancy weeks calculated?

Pregnancy weeks are calculated starting from the first day of your last menstrual period (LMP). Even though conception hasn't happened yet, this serves as the clinical baseline.

What is a trimester timeline?

Trimesters are grouped as: First Trimester (Weeks 1–13), Second Trimester (Weeks 14–27), and Third Trimester (Weeks 28–40+).

PeriodTracker

YOUR HEALTH COMPANION

Period Tracker

Pregnancy Week Calculator

Determine exactly how many weeks and days pregnant you are, which trimester you fall into, and get an estimate of your baby's size.

Calculate Weeks & Progress

First Day of Last Period (LMP)

Pregnancy Milestones

Week 5: Heart tubes begin beating.

Week 12: Vocal cords and kidneys form.

Week 20: Anatomy scan ultrasound window.