Gestational Age Calculator – Calculate Pregnancy Age by LMP
Our Gestational Age Calculator estimates how many weeks and days pregnant you are based on your last menstrual period (LMP). It’s a reliable way to track your pregnancy’s progress, understand fetal development, and anticipate your baby’s due date.
Enter Pregnancy Details
Provide the first day of your last menstrual period (LMP) to get an estimate.
Learn More About Your Pregnancy Journey
How to Use the Gestational Age Calculator
- Enter Your Last Menstrual Period (LMP): Use the input fields (DD, MM, YYYY) to provide the first day of your last period.
- Click “Calculate Gestational Age”: Press the button to get your results instantly.
- See Your Results: The calculator will show your estimated gestational age in weeks and days, your current trimester, your estimated due date, and a key development milestone for your current week.
What Is Gestational Age?
Gestational age is the standard measurement used by medical professionals to date a pregnancy. It is measured in weeks, starting from the first day of your last menstrual period (LMP). This means that by the time you have a positive pregnancy test, you are typically considered to be about 4 weeks pregnant, as conception usually occurs about two weeks after your LMP.
This method is used because most people know when their last period started, whereas the exact date of conception is often unknown. This creates a consistent timeline for everyone.
Why Knowing Your Gestational Age is Crucial
Tracking gestational age is crucial for a healthy pregnancy. It allows you and your healthcare provider to:
- Monitor Fetal Development: Ensure the baby is growing at a healthy and expected rate according to established milestones.
- Schedule Prenatal Care: Time important tests, screenings (like for genetic conditions), and ultrasounds correctly.
- Estimate the Due Date: Provide a timeline for the baby's arrival, which is essential for personal and medical planning.
- Guide Health Decisions: Inform recommendations for nutrition, exercise, and any necessary medical interventions throughout the pregnancy.
Fetal Development by Gestational Week
Here’s a summary of what’s happening as the weeks go by. Our calculator will show you the specific highlight for your current week.
| Weeks Pregnant | Trimester | Baby Development Highlights |
|---|---|---|
| 1–4 | First | Conception occurs; embryo implants in the uterus. You're officially pregnant, though you may not know it yet! |
| 5–8 | First | Baby's heart begins to beat, and all major organs like the brain and spinal cord start to form. |
| 9–13 | First | Embryo is now a fetus. Facial features develop, and the fetus can make a fist. |
| 14–17 | Second | You might feel the first flutters of movement (quickening). Baby's skeleton is hardening. |
| 18–22 | Second | Anatomy scan ultrasound is usually performed. The baby can hear sounds and swallow. |
| 23–27 | Second | Baby reaches viability (has a chance of survival if born). Lungs continue to develop rapidly. |
| 28–31 | Third | Baby can open and close their eyes and may have a full head of hair. They are gaining weight steadily. |
| 32–35 | Third | Baby practices breathing movements, and their bones are fully formed but still soft. |
| 36–40+ | Third | Baby is considered full-term. They get into position for birth, and their lungs are mature. |