Trimester Split Calculator

Calculate your pregnancy trimesters, key dates, milestones, and development stages with a professional, accurate tool.

Calculate Your Trimester Split

Your Trimester Results

What Are Pregnancy Trimesters?

Pregnancy is divided into three trimesters, each lasting about 13 weeks. Each stage brings unique fetal development and maternal changes.

First Trimester (Weeks 1–12)

Conception, embryo development, placenta formation, and vital organ development begin.

Second Trimester (Weeks 13–26)

Fetal movement, gender identification, rapid growth, and most noticeable baby development.

Third Trimester (Weeks 27–40+)

Final growth, lung maturation, weight gain, and preparation for birth.

Frequently Asked Questions

How is the trimester split calculated?

Using standard medical guidelines: 1–12 = First, 13–26 = Second, 27+ = Third.

Is this calculator accurate?

Yes, it uses globally accepted OB/GYN standards.

Can I use this with irregular periods?

Adjust your cycle length for better accuracy. For extreme irregularity, consult a doctor.

About This Tool

Professional Trimester Split

Accurate Date Calculation

OB/GYN Approved Logic

Mobile Friendly

100% Free

Related Tools

• Due Date Calculator

• Conception Date Finder

• Ovulation Calculator

• Obstetric Wheel Calculator