Pregnancy Calculator – Calculate Due Date, Trimester & Timeline

  • Adam
  • November 1, 2025

Free master pregnancy calculator. Calculate your due date, current week, and pregnancy timeline from LMP, ultrasound, conception, or IVF transfer. Access all pregnancy tools.

🤰 📅 👶

Pregnancy Calculator

Estimate your full pregnancy schedule based on your due date, last period, ultrasound date, conception date, or IVF transfer. Get comprehensive pregnancy tracking and important milestones.

📋 Quick Navigation

🤰 Calculate your pregnancy timeline! 📅
Your estimated delivery date
First day of your last menstruation
21-35 days
Date of your scan
weeks at scan
Date of conception or ovulation
Date embryo was transferred
age of embryo
Current Pregnancy Week
TBD
of 40 weeks

Due Date

—
delivery date

Current Trimester

—
trimester

Weeks Remaining

—
weeks

Progress

—
%

📊 Pregnancy Timeline

Event Estimated Date Weeks Notes
LMP — Week 0 First day of last period
Conception — Week 2 Egg fertilized
Implantation — Week 3-4 Embryo implants
First Trimester End — Week 12 Miscarriage risk drops
Anatomy Scan — Week 18-22 Detailed ultrasound
Third Trimester — Week 27 Final trimester begins
Early Term — Week 37 Labor can begin
Full Term — Week 39 Complete pregnancy
Due Date — Week 40 Estimated delivery

🤰 Pregnancy Trimesters Guide

First Trimester (Weeks 1-12)

Development: All major organs and systems form. Neural tube closes. Heart begins beating. Symptoms: Morning sickness, fatigue, breast tenderness, frequent urination. Milestones: Positive pregnancy test (weeks 3-4), heartbeat visible on ultrasound (week 6), end of high miscarriage risk (week 12).

Second Trimester (Weeks 13-26)

Development: Baby grows significantly. Bones harden. Facial features develop. Baby can hear. Symptoms: Energy returns, baby bump visible, increased appetite. Milestones: Anatomy scan (week 18-22), fetal movement felt (week 16-20), baby's sex typically determined at anatomy scan.

Third Trimester (Weeks 27-40)

Development: Brain develops rapidly. Baby positions head-down. Lungs mature. Baby gains weight. Symptoms: Back pain, swelling, Braxton-Hicks contractions, frequent urination. Milestones: Baby viable if born (week 24+), early term labor possible (week 37+), full term (week 39).

💡 Note: Gestational age (from LMP) differs from fetal age by 2 weeks. At "8 weeks" gestational age, baby is only 6 weeks old developmentally.

🎯 Key Pregnancy Milestones

Early Pregnancy (Weeks 1-8)

Week 1-2: Ovulation and conception. Week 3-4: Implantation occurs. Week 4: Positive pregnancy test (hCG detected). Week 5: Gestational sac visible on ultrasound. Week 6: Fetal pole and heartbeat visible. Week 8: All major organs forming, baby is 1 inch long.

First to Second Trimester (Weeks 9-14)

Week 9: Embryonic period ends, fetal period begins. Week 10: Facial features forming, fingers and toes visible. Week 12: First trimester screening optional, nuchal translucency measurement. Week 13: Second trimester begins, miscarriage risk significantly drops.

Mid-Pregnancy (Weeks 15-20)

Week 16: Fetal movements may be felt (quickening). Week 18-22: Anatomy scan - detailed ultrasound checking all organs, determining sex if desired. Week 20: Halfway through pregnancy!

Late Pregnancy (Weeks 21-36)

Week 24: Viability point - baby can survive with medical care if born. Week 26: Eyes open. Week 28: Third trimester begins, increased fetal movement. Week 32: Baby typically head-down.

Final Weeks (Weeks 37-40+)

Week 37: Early term - labor is safe if it begins. Week 38: Baby moves into birth canal. Week 39: Full term pregnancy. Week 40: Due date. Week 42: Postterm - induction typically offered.

❓ Frequently Asked Questions

What is the difference between gestational age and fetal age? +
Gestational age is measured from the first day of your last menstrual period (LMP), even though the baby isn't conceived until 2 weeks later. Fetal age is the actual age of the baby. So at "8 weeks" gestational age, the baby is only 6 weeks old developmentally (fetal age).
Why do doctors use 40 weeks instead of 9 months? +
Because pregnancy is measured from the first day of the last menstrual period, and using weeks provides more precision than months. 40 weeks is approximately 9 months, but weeks allow for more accurate tracking of fetal development and timing of prenatal care.
What if my due date changes at a later ultrasound? +
This is common. Early ultrasounds (before 12 weeks) are more accurate for dating than LMP. If your ultrasound shows different dating, that becomes your new due date. Later ultrasounds are less accurate for dating adjustments.
Can babies be born before 37 weeks? +
Yes, babies born before 37 weeks are considered preterm. Babies born at 34+ weeks usually do well. Before 34 weeks increases risks. Viability (chance of survival with medical care) increases significantly from week 24 onwards.
What happens if I go past my due date? +
Most pregnancies last 38-42 weeks. Going past due date is postterm pregnancy. Healthcare providers typically offer induction by 42 weeks due to increased risks. Some induce at 41 weeks. Discuss your options with your provider if you haven't delivered by your due date.
How accurate is this calculator? +
Accuracy depends on the method: LMP with regular cycles ±2 weeks, early ultrasound ±3-5 days, later ultrasound ±1-2 weeks. Only about 5% of babies arrive on the exact due date. 90% arrive within 2 weeks of the due date. Your healthcare provider provides the most accurate dating for your specific situation.
Should I use this calculator or my doctor's calculation? +
Always follow your healthcare provider's dating and medical advice. This calculator provides estimates for general information. Your doctor has access to your specific ultrasounds and medical history for accurate dating. Use this tool for educational purposes and to track approximate timelines.

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