Full term is 39-40 weeks. Early term: 37-38 weeks, Late term: 41 weeks.

Due Date Calculator | Pregnancy Due Date Estimator

📖 How to Use This Due Date Calculator

Select your calculation method (LMP, Conception Date, or Ultrasound), enter the date, and get your estimated due date, current week, trimester, and pregnancy milestones.

🤰 How Pregnancy Due Dates Are Calculated

A full-term pregnancy typically lasts about 280 days (40 weeks) from LMP. Conception usually occurs around day 14 of a 28-day cycle, so due dates are 40 weeks from LMP but only 38 weeks from conception. Naegele's Rule: Due Date = LMP + 280 days.

📊 Calculation Methods

LMP Method: Due Date = LMP + 280 days (40 weeks). Most common.
Conception Date: Due Date = Conception + 266 days (38 weeks).
Ultrasound: Most accurate (±3-5 days) from 8-12 week scan.

📅 Pregnancy Trimesters

First (Weeks 1-12): Morning sickness, fatigue, organ formation.
Second (Weeks 13-26): Energy returns, baby movement felt.
Third (Weeks 27-40): Baby grows rapidly, prepare for delivery.

💡 Important Milestones

Week 6-8: First heartbeat
Week 10-12: Nuchal translucency screening
Week 16-20: Anatomy scan
Week 24-28: Gestational diabetes screening
Week 39-41: Full term

❓ FAQ

❓ How accurate is this calculator? ▼

LMP-based calculations have ±7-10 days accuracy. First-trimester ultrasound is most accurate (±3-5 days). Only 5% of babies are born on exact due date.

❓ What if my cycle is longer than 28 days? ▼

For longer cycles, ovulation occurs later. Add the difference to your due date. Example: 35-day cycle = add 7 days.

❓ When should I have my first ultrasound? ▼

Most providers recommend first ultrasound between 8-12 weeks for accurate dating.

❓ What is full term? ▼

Early term: 37-38 weeks, Full term: 39-40 weeks, Late term: 41 weeks, Post-term: 42+ weeks.

❓ Why does due date change after ultrasound? ▼

Ultrasound measures baby's size (crown-rump length) for accurate dating. If discrepancy >5-7 days, ultrasound date is used.