Calculate your pregnancy due date from your Last Menstrual Period (LMP). Get gestational age, trimester information, and key milestones.
About Pregnancy Dating
Gestational age is calculated from the first day of your Last Menstrual Period (LMP). An average pregnancy lasts 280 days (40 weeks) from the LMP date. Your due date is estimated as LMP + 280 days. Most babies are born within 2 weeks of the due date (between 38-42 weeks). Ultrasound dating in the first trimester is more accurate than LMP-based calculation.
How to Use This Calculator
Enter the first day of your last menstrual period. The calculator will show your estimated due date, current gestational age in weeks and days, which trimester you're in, and key pregnancy milestones. Remember: this is an estimate. Your doctor can provide a more accurate due date using ultrasound.
Frequently Asked Questions
Why is my due date estimate different from my doctor's? ▼
LMP-based calculation assumes a 28-day cycle and ovulation on day 14. Ultrasound dating (especially first trimester) is more accurate. Your doctor may adjust the due date based on ultrasound measurements.
When should I expect to go into labor? ▼
The due date is an estimate. Most babies arrive within 2 weeks of the due date (38-42 weeks gestation). Only about 5% of babies are born on the exact due date. Labor before 37 weeks is premature; after 42 weeks may require medical intervention.
What are pregnancy trimesters? ▼
First Trimester (weeks 1-12): Organ development, morning sickness common. Second Trimester (weeks 13-26): Baby growth, movements felt. Third Trimester (weeks 27-40): Final weight gain, preparation for birth.
Is this calculator accurate if I have irregular periods? ▼
LMP-based calculation is less accurate with irregular cycles. If your periods are irregular, inform your doctor. An early ultrasound (8-13 weeks) provides the most accurate dating.
When can I feel baby movements? ▼
First-time mothers typically feel movement (quickening) around 18-25 weeks. Those who've been pregnant before may feel it earlier (16-20 weeks). Movements become stronger and more frequent as pregnancy progresses.