Pregnancy Week Calculator
About Pregnancy Week Calculator
Tracking Your Pregnancy Week by Week
Knowing exactly how far along you are in pregnancy is essential for tracking fetal development, scheduling prenatal appointments, and preparing for childbirth. Pregnancy is divided into three trimesters: First trimester (weeks 1-12), Second trimester (weeks 13-27), and Third trimester (weeks 28-40). Each week brings new developmental milestones for the baby, from the first heartbeat around week 6 to viable lung development around week 34.
How Gestational Age Is Calculated
Gestational age is counted from the first day of your last menstrual period (LMP), not from conception. This means you are considered 2 weeks pregnant at the time of conception. While this seems counterintuitive, it is the universal standard used by healthcare providers worldwide because LMP is a known date while conception is usually estimated.
How to Use This Calculator
Enter the first day of your last menstrual period. The calculator tells you exactly how many weeks and days pregnant you are today, which trimester you are in, and provides developmental information about your baby at this stage including approximate size and weight. It also shows a countdown to your due date and upcoming milestone dates.
Frequently Asked Questions
When do the trimesters start and end?
First trimester: weeks 1-12. Second trimester: weeks 13-27. Third trimester: weeks 28-40 (delivery). Each trimester lasts approximately 13-14 weeks.
Is gestational age different from fetal age?
Yes. Gestational age counts from LMP and is about 2 weeks more than fetal age, which counts from actual conception. Healthcare providers always use gestational age.
What is full term?
Full term is 39-40 weeks. Early term is 37-38 weeks. Late term is 41 weeks. Post-term is 42+ weeks. Babies born at 37+ weeks are generally considered term, though outcomes are best at 39-40 weeks.
