Which trimester are you in?
Calculate your current pregnancy trimester and discover what to expect. Get detailed information about milestones, symptoms, and care for each trimester.
Trimester Calculator
Enter your last menstrual period date to find out which trimester you're in
Medical Disclaimer
This calculator provides estimates for educational purposes only. Results should not replace professional medical advice. Always consult with your healthcare provider for personalized guidance and medical decisions during pregnancy.
Calculation Accuracy
Methodology
Uses standard obstetric trimester definitions: First (1-13 weeks), Second (14-27 weeks), Third (28-40+ weeks). Calculations based on last menstrual period dating following ACOG guidelines.
Important Considerations
- •Based on 40-week pregnancy timeline
- •Individual pregnancy experiences may vary
- •Some symptoms may occur outside typical trimester ranges
- •Medical dating may differ from LMP dating
- •Trimester divisions are medical approximations
💚 Trimester divisions help healthcare providers track pregnancy progress and schedule appropriate care at each stage.
Trimester Overview
First Trimester
Weeks 1-13: Organ development
Second Trimester
Weeks 14-27: Growth & movement
Third Trimester
Weeks 28-40+: Birth preparation
Related Pregnancy Tools
Frequently Asked Questions
Common questions about trimester calculation and pregnancy stages
Which trimester am I in at different weeks?
First trimester: weeks 1-13, Second trimester: weeks 14-27, Third trimester: weeks 28-40+. The trimester divisions help track major developmental phases and medical care needs throughout pregnancy.
How do you calculate which trimester I'm in?
Trimester calculation is based on your pregnancy week, which counts from the first day of your last menstrual period (LMP). This is the standard medical method used by healthcare providers worldwide.
What happens in each trimester?
First trimester: major organ development, morning sickness, early prenatal care. Second trimester: increased energy, baby movements, anatomy scan. Third trimester: rapid growth, labor preparation, weekly checkups.
Why is it important to know which trimester I'm in?
Different trimesters have specific prenatal care requirements, screening tests, and developmental milestones. Knowing your trimester helps you understand what to expect and when to schedule important appointments.
Can trimester timing vary between pregnancies?
The trimester weeks remain the same (1-13, 14-27, 28-40+), but individual experiences vary. Some women may feel second trimester energy earlier or later, and symptoms can differ between pregnancies.