Pregnancy Due Date Calculator

Calculate your estimated due date based on your last menstrual period or conception date

Calculation Method

Choose Method

First Day of Last Period

Average Cycle Length (days)

Typical cycle is 28 days

Estimated Due Date

Monday, December 14, 2026

You are currently

8 weeks 4 days

pregnant

First Trimester

Weeks 1-12

Days Until Due Date

220

Pregnancy Milestones

Week 4

Positive pregnancy test possible

✓

Week 8

First prenatal visit, heartbeat detectable

✓→

Week 12

End of first trimester, miscarriage risk decreases

Week 20

Anatomy scan, may learn baby's sex

Week 24

Viability milestone

Week 28

Third trimester begins

Week 36

Baby considered early term

Week 40

Due date!

Understanding Your Due Date

Your estimated due date (EDD)is calculated as 40 weeks (280 days) from the first day of your last menstrual period (LMP). This is based on Naegele's Rule, which assumes a 28-day menstrual cycle with ovulation occurring on day 14.

How Accurate is the Due Date?

Only about 5% of babies are born on their exact due date. Most babies are born between 37 and 42 weeks of pregnancy. Your due date is an estimate, not a deadline. Many factors can affect when your baby arrives.

Full Term: 39-40 weeks (optimal time for delivery)
Early Term: 37-38 weeks (baby is developed but not optimal)
Late Term: 41 weeks (monitoring increases)
Post Term: 42+ weeks (induction often recommended)

The Three Trimesters

First Trimester (Weeks 1-12): Major organs form, morning sickness common, miscarriage risk highest. First prenatal visit and early ultrasound.

Second Trimester (Weeks 13-26): Energy returns, baby movements felt, anatomy scan at 20 weeks. Often called the "honeymoon period."

Third Trimester (Weeks 27-40): Rapid growth, increased discomfort, preparation for birth. Frequent prenatal visits.

Important: This calculator provides an estimate. Your healthcare provider may adjust your due date based on ultrasound measurements, especially from early pregnancy scans.

Prenatal Care Timeline

First Trimester

• First prenatal visit (8-10 weeks)
• Blood tests and health history
• Dating ultrasound
• Prenatal vitamins with folic acid
• Genetic screening options

Second Trimester

• Monthly prenatal visits
• Anatomy scan (18-22 weeks)
• Glucose screening (24-28 weeks)
• Feel baby movements
• Consider childbirth classes

Third Trimester

• Bi-weekly visits (28-36 weeks)
• Weekly visits (36+ weeks)
• Group B strep test (35-37 weeks)
• Finalize birth plan
• Pack hospital bag

Important Tests

• Blood type and Rh factor
• STD screening
• Ultrasounds (dating & anatomy)
• Glucose tolerance test
• Fetal monitoring (if needed)

Frequently Asked Questions

How is my due date calculated?

The due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period. This assumes a 28-day cycle with ovulation on day 14. Your doctor may adjust this based on early ultrasound measurements.

Can my due date change?

Yes, your healthcare provider may adjust your due date based on ultrasound measurements, especially from scans done in the first trimester (most accurate). After 20 weeks, due dates are rarely changed unless there's a significant discrepancy.

What if I don't know my last period date?

Your doctor can estimate your due date using an early ultrasound (dating scan). The crown-rump length measured between 8-13 weeks is very accurate for determining gestational age and due date.

What happens if I go past my due date?

Most providers will monitor you closely after 40 weeks with non-stress tests and ultrasounds. Many will recommend induction between 41-42 weeks to reduce risks. Only 10% of pregnancies go past 42 weeks naturally.

Is it safe to deliver before my due date?

Babies born at 37+ weeks are considered term, but 39-40 weeks is optimal for baby's development. Unless medically necessary, it's best to let labor start naturally. Early term babies (37-38 weeks) have slightly higher risks than full-term babies.