🤰 Pregnancy Due Date Calculator

Calculate your estimated due date and track every week of your pregnancy. Enter your last period date, conception date, or ultrasound result to get your due date, current trimester, and key milestones.

🤰 Calculate Your Due Date

First Day of Last Menstrual Period

Average Cycle Length (days)

🍼 Your Pregnancy Summary

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Estimated Due Date (EDD)

Current Week—

Trimester—

Days Until Due Date—

Weeks Remaining—

Safe Delivery Window—

Conception Date (est.)—

📖 How Is Your Due Date Calculated?

A typical pregnancy lasts 280 days (40 weeks) from the first day of your last menstrual period (LMP), or 266 days (38 weeks) from conception. The most common method is Naegele's Rule:

                EDD = LMP + 280 days

                or: LMP + 9 months + 7 days

Trimester Breakdown

First Trimester (Weeks 1–13): Organ development, morning sickness common, highest miscarriage risk
Second Trimester (Weeks 14–27): Energy returns, baby movements felt (~18–22 weeks), anatomy scan
Third Trimester (Weeks 28–40): Rapid growth, birth preparation, GBS test, weekly visits

⚕️ Medical Disclaimer

This calculator provides estimates only. Only 5% of babies are born on their exact due date — most arrive within a 2-week window. Always confirm your due date with your OB/GYN or midwife via ultrasound, which is more accurate than LMP calculation.

📋 Key Prenatal Milestones & Appointment Schedule

Week	Milestone / Test	What to Expect
6–8 weeks	First prenatal visit	Confirmation ultrasound, blood tests, due date
10–13 weeks	First trimester screening	Nuchal translucency ultrasound, NIPT blood test
18–20 weeks	Anatomy scan (Level 2)	Baby's anatomy check, can learn sex
24–28 weeks	Glucose tolerance test	Gestational diabetes screening
28 weeks	Rh factor / antibodies	Rhogam shot if Rh negative
35–37 weeks	GBS culture	Group B strep screening
36+ weeks	Weekly visits begin	Cervical checks, baby position assessment
39–40 weeks	Full term	Delivery planning, membrane sweep if needed

💡 Real-World Examples & Use Cases

Due dates use Naegele's rule: about 280 days (40 weeks) from the last menstrual period (LMP).

LMP on January 1

Estimating a due date from a last period starting January 1.

Result: Add 280 days → due date ≈ October 8 (40 weeks).

How far along am I?

Counting weeks from the LMP, not from conception.

Result: Pregnancy is dated from LMP, so you're considered ~2 weeks pregnant at conception.

Trimesters

Roughly equal thirds of the 40 weeks.

Result: 1st: weeks 1–13, 2nd: 14–27, 3rd: 28–40.

⚠️ Common Mistakes & Pro Tips

Treating the due date as exact: Only ~5% of babies arrive on the due date; a 2-week window is normal.
Dating from conception: Pregnancy is dated from the last period, about 2 weeks before conception.
Skipping prenatal care: Calculators estimate; your provider confirms dating with ultrasound.

🔍 People Also Ask

How is the due date calculated?

Add 280 days (40 weeks) to the first day of your last menstrual period.

How accurate is the due date?

Only about 5% of babies arrive exactly on it; a two-week window is normal.

How many weeks pregnant am I?

Counted from your last period — you're considered ~2 weeks along at conception.

❓ Frequently Asked Questions

How accurate is the LMP due date calculation? −

The LMP (last menstrual period) method is accurate within ±2 weeks for women with regular 28-day cycles. It can be less accurate for women with irregular cycles. First-trimester ultrasound (before 13 weeks) is the most accurate dating method, typically accurate to within ±5–7 days. When LMP and ultrasound dates differ by more than 7–10 days, doctors usually go with the ultrasound date.

What is a full-term pregnancy? +

A full-term pregnancy is defined as 39 weeks 0 days through 40 weeks 6 days. Babies born at 37–38 weeks are 'early term,' while those born at exactly 37 weeks or earlier are premature. Late term is 41 through 41w6d, and post-term is 42 weeks and beyond. Most doctors recommend inducing labor at 41–42 weeks if labor hasn't begun naturally.

Can my due date change? +

Yes. Your due date may be adjusted after an ultrasound if the baby's measurements don't match the LMP-based estimate. This is especially common if you conceived later in your cycle or have irregular periods. Only about 4–5% of babies are actually born on their calculated due date — most arrive within a 2-week window on either side.

What week is safe to deliver? +

Babies born at 39–40 weeks (full term) have the best outcomes. Earlier deliveries carry increased risks: 37–38 weeks (early term) has slightly higher NICU risk; before 37 weeks is premature. However, sometimes early delivery is medically necessary due to preeclampsia, placental issues, or other complications. Your care team will guide you on the safest timing.

What are the signs of labor? +

Early signs include: regular contractions that intensify and get closer together (unlike Braxton Hicks which are irregular), water breaking (rupture of membranes), bloody show (mucus plug discharge), and lower back pain that radiates to the abdomen. If your water breaks, contractions are 5 minutes apart lasting 60 seconds, or you have heavy bleeding, go to the hospital immediately.

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