Pregnancy Trimester Calculator
Calculate your current trimester, due date, and important pregnancy milestones
Understanding Pregnancy Trimesters
First Trimester (Weeks 1-13)
The first trimester is crucial for fetal development. During this time, the baby's major organs begin to form. Many women experience morning sickness and fatigue during these early weeks.
Second Trimester (Weeks 14-27)
Often called the "golden period" of pregnancy, the second trimester typically brings relief from early symptoms. The baby grows rapidly, and many women begin to show their pregnancy bump.
Third Trimester (Weeks 28-40)
The final stretch of pregnancy brings significant growth and preparation for birth. The baby gains weight rapidly, and the mother may experience increased discomfort as the due date approaches.
Why Use a Pregnancy Trimester Calculator?
Our pregnancy trimester calculator helps you:
- Determine exactly which pregnancy trimester you're in
- Calculate your estimated due date based on medical standards
- Track important pregnancy milestones and development stages
- Plan for prenatal appointments and tests at the right times
- Understand when to expect certain symptoms and changes
Important Disclaimer
This pregnancy trimester calculator provides estimates based on standard medical guidelines. It is not a substitute for professional medical advice. Always consult with your healthcare provider for personalized information about your pregnancy.
Related Resources
ACOG: Fetal Development
American College of Obstetricians and Gynecologists guide to pregnancy stages
Mayo Clinic: Prenatal Care
Comprehensive prenatal care information by trimester
CDC Pregnancy Information
CDC resources for healthy pregnancy
WHO: Pregnancy Facts
World Health Organization pregnancy information
NHS Pregnancy Guide
UK National Health Service pregnancy week-by-week
MedlinePlus Pregnancy
US National Library of Medicine pregnancy resources
March of Dimes
Nonprofit organization supporting healthy pregnancies
Planned Parenthood
Pregnancy information and resources
HealthyChildren.org
American Academy of Pediatrics pregnancy resources
How Our Pregnancy Trimester Calculator Works
Enter Your Date
Provide either your last menstrual period date, conception date, or ultrasound date. Our calculator works with all common pregnancy dating methods .
Automatic Calculation
We instantly calculate your current trimester, weeks pregnant, estimated due date, and all important trimester boundaries.
Detailed Results
Receive comprehensive information about your pregnancy timeline, including key milestones for each trimester.
Frequently Asked Questions
Our pregnancy trimester calculator makes it easy to determine your current trimester. Simply enter your last menstrual period date, conception date, or ultrasound date, and the calculator will automatically determine which trimester you're in based on standard medical guidelines that divide pregnancy into three equal parts.
While our calculator provides a good estimate based on standard pregnancy calculations (280 days from LMP), the most accurate due date is typically determined by an early ultrasound, especially one performed in the first trimester. Healthcare providers may adjust your due date based on ultrasound measurements if they differ significantly from your LMP-based calculation.
Yes, you can use either the conception date or ultrasound date options if you don't know your last menstrual period. If you're unsure about all dates, we recommend consulting with your healthcare provider who can help determine your pregnancy timeline through clinical examination and possibly ultrasound.
The first trimester ends at week 13 of pregnancy. Our calculator will automatically show you the exact date your first trimester ends when you enter your pregnancy information. This is helpful for knowing when certain prenatal tests should be completed and when many women start feeling relief from early pregnancy symptoms.
Gestational age is measured from the first day of your last menstrual period (LMP), while fetal age (or conceptual age) is measured from the actual date of conception. Since conception typically occurs about two weeks after the LMP, fetal age is usually about two weeks less than gestational age. Most healthcare providers use gestational age for consistency, as LMP is typically more reliably known than conception date.