Pregnancy Calculator l Find Your Due Date & Track Every Week

Expecting a baby? Our free online pregnancy calculator helps you estimate your due date, find out how far along you are, and track your full pregnancy timeline week by week. Simply enter the first day of your last menstrual period (LMP) and get your estimated delivery date, current gestational age, and trimester stage — all in seconds.

What Is an Expected Delivery Date (EDD)?

Your Expected Delivery Date (EDD) is the estimated date your baby is most likely to arrive. It is calculated as 40 weeks (280 days) from the first day of your last menstrual period. Only about 5% of babies are born exactly on their due date — your EDD is a planning guide, not a fixed deadline. Factors like cycle regularity, ultrasound measurements, and conception timing can all slightly affect this estimate.

Why Use This Pregnancy Due Date Calculator?

Knowing your due date early helps you take control of your prenatal journey. With this calculator you can:

• Find out exactly how many weeks pregnant you are today
• Estimate your delivery date based on your LMP
• Identify which trimester you are currently in
• Plan your prenatal appointments and anatomy scan
• Track your baby’s weekly development milestones
• Know when to take a pregnancy test after a missed period

How Is Pregnancy Due Date Calculated?

Last Menstrual Period (LMP) Method

This is the most widely used method and the one our calculator uses. Enter the first day of your last period, and the tool counts forward 280 days (40 weeks) to estimate your due date. This method works best when your menstrual cycle is regular, typically around 28 days.

Conception Date Method

If you know your conception date through ovulation tracking or fertility treatment, your due date is calculated by adding 266 days (38 weeks) from that date. This is particularly useful for couples who monitor their fertile window closely.

IVF Due Date Calculation

For IVF pregnancies, the due date is calculated from your embryo transfer date. A Day 3 transfer adds 263 days; a Day 5 (blastocyst) transfer adds 261 days. IVF calculations are among the most precise because the exact date of fertilization is known.

Ultrasound Dating

A first-trimester ultrasound measures your baby’s crown-rump length (CRL) to confirm or adjust gestational age. When your LMP is uncertain or your cycle is irregular, ultrasound dating is considered the most accurate method available.

How Many Weeks Pregnant Am I?

Gestational age is measured in weeks and days from the first day of your LMP — not from your conception date. This is why pregnancy is tracked as 40 weeks even though actual fertilization happens around week 2.

Enter your LMP into the calculator above and instantly see:

• Your current week and day of pregnancy
• Your trimester stage
• How many weeks remain until your due date

Pregnancy Week by Week — Trimester Overview

First Trimester: Weeks 1–12 This is the stage of rapid cell division and early organ formation. Common symptoms include nausea, fatigue, and breast tenderness. Your first prenatal visit and early ultrasound typically occur during this period.

Second Trimester: Weeks 13–27 Often called the most comfortable trimester. Energy returns, your baby bump becomes visible, and the anatomy scan around week 20 checks your baby’s development in detail. Many parents learn the baby’s sex at this stage.

Third Trimester: Weeks 28–40 Your baby gains weight rapidly and prepares for birth. You may experience Braxton Hicks contractions, increased back pressure, and shortness of breath as your baby drops into position. Birth planning and hospital preparation happen here.

Weekly Baby Development Milestones

• Week 6 — Heartbeat detectable on ultrasound
• Week 8 — Baby is roughly the size of a raspberry
• Week 12 — Fingers, toes, and facial features fully formed
• Week 16 — Baby begins making facial expressions
• Week 20 — Baby can hear sounds from outside the womb
• Week 28 — Eyes begin to open; sleep and wake cycles develop
• Week 30 — Baby starts storing fat to regulate body temperature after birth
• Week 36 — Early term; lungs nearly mature
• Week 40 — Full term and ready for birth

When to Take a Pregnancy Test

Home pregnancy tests detect hCG (human chorionic gonadotropin), a hormone produced after a fertilized egg implants in the uterus. Most tests become reliable 10–14 days after ovulation or the day of your missed period. Testing too early may give a false negative even if you are pregnant. If you get a negative result but your period still hasn’t arrived, retest after 2–3 days.

Frequently Asked Questions

How long is a full-term pregnancy? A full-term pregnancy is 40 weeks, roughly 9 months and one week from your LMP.

How is pregnancy calculated week by week? Pregnancy weeks are counted from the first day of your last menstrual period. Week 1 begins on that day, and each new week starts 7 days later.

Can my due date change after a ultrasound? Yes. If your first-trimester ultrasound measurements differ from your LMP estimate by more than a few days, your provider may adjust your due date accordingly.

Is an online pregnancy calculator accurate? LMP-based calculators provide a reliable estimate when your cycle is regular. For the most accurate dating, always confirm with your OB-GYN or midwife through an ultrasound.

What if my baby comes early or is overdue? Babies born between 37–42 weeks fall within the normal delivery range. Births before 37 weeks are considered preterm. After 42 weeks, your provider may recommend induction.

What is the difference between induction and natural labor? Natural labor starts spontaneously when your body and baby are ready. Medical induction uses methods such as Pitocin, membrane sweeping, or cervical ripening to initiate labor when continuing the pregnancy carries a risk.

Calculate Your Due Date Now

Use the free Serenity Choice Health pregnancy calculator above — enter the first day of your last menstrual period and get your estimated due date, gestational age, and full pregnancy timeline instantly.

Note: This calculator is for informational purposes only and does not replace professional medical advice. Always consult your OB-GYN or midwife for personalized pregnancy care.