Pregnancy calculator By Weeks helps you determine your pregnancy progress week by week and provides an accurate estimate of your due date.

Simply enter the date of your last menstrual period, and your current pregnancy week along with all results will appear instantly.

Pregnancy Calculator by Weeks

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Pregnancy by Weeks Table

Month	Weeks of Pregnancy	Trimester	Key Developments
Month 1	Week 1 – Week 4	First Trimester	Fertilization, implantation, early organ formation.
Month 2	Week 5 – Week 8	First Trimester	Heartbeat begins, facial features start forming.
Month 3	Week 9 – Week 13	First Trimester	Organs fully form, baby starts moving.
Month 4	Week 14 – Week 17	Second Trimester	Gender may be visible, rapid growth.
Month 5	Week 18 – Week 22	Second Trimester	Feel baby movements, hair starts growing.
Month 6	Week 23 – Week 27	Second Trimester	Eyelids and eyebrows form, baby responds to sounds.
Month 7	Week 28 – Week 31	Third Trimester	Lung development, rapid weight gain.
Month 8	Week 32 – Week 35	Third Trimester	Brain development accelerates, baby prepares for birth position.
Month 9	Week 36 – Week 40 (or birth)	Third Trimester	Baby is fully developed and ready for birth.

Explore all stages of your baby’s development with images and key milestones for both you and your baby throughout your pregnancy journey.

how to calculate pregnancy weeks ?

Gestational Age: This is the most commonly used measurement. It is calculated from the first day of your last menstrual period (LMP), not from the date of conception. Ovulation and fertilization are assumed to occur approximately 14 days after the start of the menstrual cycle.
Fetal Age: This is calculated from the date of conception and is about two weeks shorter than gestational age. For example, if the gestational age is 6 weeks, the fetal age would be approximately 4 weeks.

Why is gestational age used instead of fetal age?
Gestational age is preferred because identifying the date of the last menstrual period is easier and more accurate than pinpointing the exact date of conception.

How long is a full term Pregnancy in Weeks ?

A full-term pregnancy lasts approximately 40 weeks (280 days) from the first day of your last menstrual period and is divided into three trimesters, spanning about nine months.

First Trimester (0–13 Weeks):
Begins at week one and includes early embryonic development, organ formation, and the first detection of a heartbeat.
Second Trimester (14–27 Weeks):
Features significant fetal growth, the first noticeable movements, and the development of facial features.
Third Trimester (28–40 Weeks):
Marks the final stages of growth, organ maturation, and the baby preparing for birth.

Why Pregnancy is Measured in Weeks, Not Months

Weeks provide a more accurate measurement because months vary in the number of days (28–31 days), whereas weeks are always 7 days long. Using weeks helps avoid confusion and ensures precise tracking of developmental milestones and important health checkups.

If you need to visit an OB-GYN or have questions about your pregnancy, book an appointment at Dr. Mohamed Wafeek’s clinic today.