Delivery Date Calculator

Introduction

This Delivery Date Calculator tells you when your baby is likely to be born. Enter one date and it returns your estimated due date.

You can pick the method that fits what you know:

• Last menstrual period (LMP): the first day of your last period, plus your cycle length
• Conception date: the day you know you conceived
• Due date: work backward from a due date you already have
• Ultrasound: the scan date and the weeks and days your doctor measured
• IVF transfer: the transfer date and the age of the embryo (day 3, 5, or 6)

Along with your due date, you will see how far along you are right now, how much time is left, and the dates of key pregnancy milestones. These include your first heartbeat scan, the end of the first trimester, when the baby's sex may be seen, and your full term window. A timeline and chart show each trimester, and a step-by-step section shows the math behind every number.

This is an estimate, not a promise. Only about 1 in 20 babies arrive on the exact due date.² Always talk to your doctor or midwife for real medical advice.

How to use our Delivery Date Calculator

Pick how you want to work out your due date, then fill in the dates for that method. The calculator shows your estimated due date, your conception date, how far along you are, weeks left, key pregnancy milestones, and your trimester dates.

Calculation Method: Choose how you want to find your due date. You can use your last period, a conception date, a due date you already know, an ultrasound scan, or an IVF transfer. Only the boxes you need will show up.

First Day of Last Menstrual Period: Enter the first day your last period started. Use today's date or an earlier one. This is the most common way to date a pregnancy.

Average Cycle Length (days): Type how many days there are from the start of one period to the start of the next. Most people are close to 28 days. Enter 20 to 45 days for the best result.

Known Conception Date: Enter the day you think you conceived. This works well if you tracked ovulation. The date must be today or earlier.

Your Known Due Date: If your doctor already gave you a due date, type it here. The calculator works backwards to find your last period, conception date, and milestones. Future dates are fine.

Date of Ultrasound Scan: Enter the day you had your scan. It must be today or an earlier date.

Gestational Age at Time of Scan: Type the weeks and days your scan report gave you. Weeks can be 1 to 42, and days can be 0 to 6. For example, 8 weeks and 3 days.

Embryo Transfer Date: Enter the day your embryo was transferred. This is used for IVF pregnancies. The date must be today or earlier.

Embryo Age at Transfer: Pick Day 3, Day 5, or Day 6. This is how old the embryo was on transfer day, and it changes your due date by a few days.

Click Calculate to see your results. Click Start Over to clear the form and try a new date.

What Is a Delivery Date (Due Date)?

Your delivery date, also called your estimated due date (EDD), is the day your baby is most likely to be born. A full pregnancy lasts about 280 days, or 40 weeks, counting from the first day of your last menstrual period (LMP).³ Doctors use this date to track your baby's growth, plan tests, and know when labor is on time.

How Due Dates Are Figured Out

There are a few common ways to find a due date. Each one starts from a different known date:

• Last menstrual period (LMP): Add 280 days to the first day of your last period.¹ This is called Naegele's rule. It assumes a 28-day cycle with ovulation on day 14.¹ If your cycle is longer or shorter than 28 days, the date shifts by that difference.
• Conception date: Add 266 days (38 weeks) to the day the egg was fertilized.
• Ultrasound: A scan measures the baby and gives a gestational age in weeks and days. The due date is set from there. Scans in the first trimester, up to 13 weeks and 6 days, are the most exact.¹
• IVF transfer: The date is based on the transfer day and the age of the embryo. A Day 5 embryo adds 261 days and a Day 3 embryo adds 263 days.¹ A Day 6 embryo adds 260 days.

Gestational Age vs. Fetal Age

Gestational age is counted from your last period, so you are already "2 weeks pregnant" before the egg is even fertilized.² Fetal age is counted from conception and is about 2 weeks less. Doctors almost always use gestational age.

The Three Trimesters

Pregnancy is split into three parts:

• First trimester (up to 13 weeks and 6 days): Major organs form.² Morning sickness and tiredness are common. A heartbeat can usually be seen on a vaginal ultrasound at 6 to 7 weeks.⁵
• Second trimester (14 weeks 0 days to 27 weeks 6 days): This is a time of rapid growth and development.² Many people feel better, and you may feel the baby move. The standard ultrasound exam is usually done at 18 to 22 weeks, and it may show the baby's sex if the baby is in a good position.⁷
• Third trimester (28 weeks 0 days to birth): The baby gains weight and the organs mature so they are ready to work after birth.²

Key Pregnancy Milestones

hCG, the hormone a pregnancy test looks for, can show up in blood and urine as early as 10 days after conception.⁶ Most home tests will not show a pregnancy until your period is late.⁶ Losing a pregnancy before 13 completed weeks is called early pregnancy loss, and it happens in about 10 of every 100 known pregnancies.⁹ A baby born from 37 weeks 0 days to 38 weeks 6 days is early term, from 39 weeks 0 days to 40 weeks 6 days full term, from 41 weeks 0 days to 41 weeks 6 days late term, and from 42 weeks 0 days postterm.⁴

Remember: It's an Estimate

Only about 1 in 20 babies are born on their exact due date.² Your doctor or midwife may change your due date after an early ultrasound.¹ Always use their date for medical care.