Pregnancy Due Date Calculator: Accurate Gestational Age Tracking

April 2026 Velocees Pro Team 8 min read

Pregnancy due date calculation marks the beginning of one of life's most transformative journeys. While only 4% of babies arrive exactly on their due date, knowing the target date helps schedule prenatal care.

How Due Dates Are Calculated

Naegele's Rule:
Due Date = LMP + 1 year - 3 months + 7 days
Or: Add 280 days (40 weeks) to LMP

Pregnancy Trimesters

First Trimester (Weeks 1-12): Major organs forming, neural tube closes
Second Trimester (Weeks 13-27): Gender visible, anatomy scan at week 20
Third Trimester (Weeks 28-40): Lung maturation, viability at 37 weeks

Planning Tip: Prepare for a 4-week window (38-42 weeks). Pack hospital bags by 36 weeks and notify employers of flexibility around the due date.