Pregnancy Due Date Calculator and Conception Calculator (2024)

Pregnancy > Due Date Calculator

Pregnancy Due Date Calculator and Conception Calculator (1)

When is your baby due? Use this pregnancy calculator to find your due date based on the date of your last menstrual period, conception date, IVF three-day or five-day transfer date, or date of your last ultrasound.

Pregnancy Due Date Calculator and Conception Calculator (2)

byCatherine Donaldson-Evans

Pregnancy Due Date Calculator and Conception Calculator (4) Medically Reviewed by Aaron Styer, M.D.

| September 15, 2023

How to Calculate Your Due Date

  • What is an estimated due date during pregnancy?
  • First day of last period
  • Conception date
  • IVF transfer date
  • Ultrasound scan
  • Can I plan my due date?
  • Can my due date change?
  • Other resources

What is an estimated due date during pregnancy?

Your due date (also known as your estimated due date) is a calculation of when you're expected to give birth. Your EDD is important for you to know as you prepare to welcome your baby.

But remember, it's only an estimated due date, not a deadline for your baby to arrive. Just 4 percent of babies are born on their EDD.

Our pregnancy Due Date Calculator (or estimated Due Date Calculator) can help. Here’show to calculate your due date using your last period, conception date, IVF transfer date, or timing of your last ultrasound.

First day of last period

Most pregnancies last around 40 weeks (or 38 weeks from conception), so typically the best way to estimate your due date is to count 40 weeks, or 280 days, from the first day of your last menstrual period (LMP).You can also subtract three months from the first day of your last period and add seven days.Or choose "last period" from the choices in our Due Date Calculator menu, above.

The first day of your LMP is how most health care providers estimate a baby's due date.

Conception date

If you've been trackingovulation symptomsor have been using ovulation test strips, you may be able to use your conception date to see how far along you are and when baby is likely to arrive.

Just add 266 days to get your estimated due date. Or select "conception date" and let our pregnancy Due Date Calculator do the math for you.

Wondering when your baby was conceived? Use the Conception Date Calculator below to find out the most likely date.

IVFtransfer date

If you conceived throughin vitro fertilization (IVF), you cancalculate your due date using your IVF transfer date. Most embryo transfers occur either three days or five days after egg retrieval and fertilization.

If you had a day-three transfer, count 263 days from the transfer date to calculate your due date, and if you had a day-five transfer, count 261 days. Or use ourIVF Due Date Calculator to find out the big day!

Ultrasound scan

Even if you can’t pinpoint when you conceived, forget the day of your last menstrual period, or aren’t sure when ovulation occurred, the date of an early ultrasound, if you have one, can help your practitioner determine your due date at your first prenatal appointmentor another prenatal visit in your first trimester.

The timing of an early ultrasoundcan sometimes more accurately date the pregnancy than your LMP and other methods. Just choose "ultrasound" from our Due Date Calculator choices.

Just be aware, however, that not all women get an early ultrasound. Some practitioners perform them routinely, but others only recommend one if your periods are irregular, you're 35 or older, you have a history of miscarriages or pregnancy complications, or the due date can’t be determined based on your physical exam and LMP.

Other clues can help your health care provider figure out how far along you are and better pinpoint your due date at your prenatal check-ups.

  • Pregnancy milestones such as the first time thebaby'sheartbeat is detected (around week 9 or 10, though it can vary) and when you first feelfetal movement (on average between 18 and 22 weeks, but it can be earlier or later), can give clues as to whether your due date is accurate.

  • Your fundal height, which is the measurement from your pubic bone to the top of your uterus, is checked by your practitioner at each prenatal visit and helps confirm your due date.

  • The size of your uterus, which will be noted when your initial internal pregnancy exam is performed, can also be a factor in pinpointing the EDD.

Can I plan my due date?

Whether you're trying to avoid being very pregnant in the middle of summer or are a teacher who wants to maximize time off with your little one, you can try to time when you conceive in order to "plan" your due date.

But even if you're one of the lucky ones who's able to get pregnant when she really wants to, just remember that you probably won't be able to map out exactly when you'll give birth to the day (or even the week or month!).

Still, you can try our Ovulation Calculator, which uses the date of your last menstrual period and your typical cycle length to discover the days you're most likely to be fertile and increase your chances of conceiving.

Can my due date change?

Yes, your due date can change. While it’s definitely not a reason to worry, your doctor may change your due date for a number of reasons as your pregnancy progresses.

It may be that you haveirregular periods and your early ultrasound dating was off, or that your first ultrasound was in the second trimester.

It could also be because yourfundal height is abnormal, or your levels of alpha-fetoprotein (AFP), a protein made by the baby, are outside the usual range. Talk to your practitioner if you have any questions or concerns.

Other resources

  • Early Pregnancy Symptoms
  • Your Pregnancy, Week-by-Week
  • Baby Names
  • Chinese Gender Predictor
  • Ovulation Calculator
  • Baby Registry Builder

FAQs About Due Dates

Pregnancy lasts 40 weeks from the start of your last period. It’s likely that you’ll give birth a little before or after 40 weeks, but this estimate helps healthcare providers time your prenatal care. Your due date may be adjusted if you have an ultrasound or testing that shows your pregnancy is further along than you thought.

When you calculate your due date with our Due Date Calculator tool, you’ll also find out how many weeks pregnant you are. And if you download the What to Expect app, you can easily keep track of how far along you are each day.

That depends! Your provider may change your due date if an ultrasound shows your baby is significantly bigger or smaller than expected based on your last menstrual period. Usually you can expect your due date to stay the same, but remember it’s just an estimate.

  1. American College of Obstetricians and Gynecologists,Methods for Estimating the Due Date, 2022.
  2. Stanford Children's Health,Calculating a Due Date, 2023.
  3. What to Expect When You're Expecting, 5th edition, Heidi Murkoff.
  4. What to Expect Before You're Expecting, 2nd edition, Heidi Murkoff.
  5. WhatToExpect.com, Pregnancy Week-by-Week, 2023.
  6. WhatToExpect.com, 8 Ovulation Symptoms to Detect Your Most Fertile Days, January 2023.
  7. WhatToExpect.com, Why Your Doctor May Change Your Due Date, January 2023.
  8. WhatToExpect.com, How Many Weeks, Months and Trimesters in a Pregnancy?, May 2022.
  9. WhatToExpect.com, In VitroFertilization (IVF), March 2022.
  10. WhatToExpect.com, Birth Symbols by Month: Zodiac, Birthstone, Flower and Tree, September 2018.
  11. WhatToExpect.com, Your Guide to Prenatal Appointments, August 2022.
  12. Centers for Disease Control and Prevention, ART Success Rates, June 2022.
  13. Mayo Clinic, Prenatal Care: First Trimester Visits, August 2022.

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Pregnancy Due Date Calculator and Conception Calculator (2024)

FAQs

How do you calculate due date if I know when I conceived? ›

In cases where the date of conception is known precisely, such as with in vitro fertilization, the EDD is calculated by adding 266 days to the date of conception.

How to find out when a baby was conceived? ›

Ovulation usually occurs about two weeks after your menstrual period and lasts for two or three days. This means you can sometimes determine when you conceived based on your ovulation cycles — simply determine when your last menstrual period was, and add approximately two weeks.

How accurate is a conception calculator? ›

Online calculators do not always produce reliable outcomes due to varying cycle lengths and not knowing the actual conception date. Also, there may be spotting in early pregnancies, which many women mistake for their period.

What is the most accurate way to calculate pregnancy due date? ›

Your due date is 40 weeks after the day you started your last period. This is the most reliable way to calculate your due date on your own at home, but it still isn't perfect.

Can I calculate the day I conceived? ›

Therefore, if you know the first day of period, you can add 11 to 21 days to this day to have an idea of when conception occurred. For example, if you are pregnant and your last period started on March 5, that means you likely conceived between March 16 and 26.

How am I 4 weeks pregnant if I conceived 2 weeks ago? ›

Week 4 of pregnancy

For example, a fertilised egg may have implanted in your womb just 2 weeks ago, but if the first day of your last period was 4 weeks ago, this means you're officially four weeks pregnant! Pregnancy normally lasts from 37 weeks to 42 weeks from the first day of your last period.

Can an ultrasound tell you the exact date of conception? ›

While gestational age can be estimated using ultrasound technology, conceptional age can remain a bit more elusive, depending on how many sexual encounters you had during your most recent cycle and when those were.

Are conception dates 100% accurate? ›

In general, there are a few ways to determine your conception date. No method is 100% accurate, but some are more reliable than others. The first way to find out your conception date is to determine when you were last ovulating.

Can you tell if conception was successful? ›

However, the truth is there is no such thing as a definitive sign of implantation. That's the long and short of it. The only way to know for sure if you are pregnant is by waiting to take the official pregnancy test when your doctor recommends (typically around two weeks after the transfer).

Can my conception date be wrong? ›

You may have simply conceived earlier or later than you thought you did (which can happen if your cycle is at all irregular or if you remembered your last menstrual period date incorrectly).

Is it better to calculate due date from conception or last period? ›

The unborn baby spends around 38 weeks in the uterus, but the average length of pregnancy, or gestation, is counted at 40 weeks. Pregnancy is counted from the first day of the woman's last period, not the date of conception which generally occurs 2 weeks later.

What day was I conceived? ›

Last Menstrual Period

Conception usually occurs around 11-21 days after the first day of the last period of a woman who has a regular period. The estimation of conception date is based on this, but is rarely ever exact since it is difficult to know exactly when ovulation occurs.

How accurate is due date if you know date of conception? ›

Even if you carefully tracked ovulation and know when your baby was conceived, your due date is still an estimate, because every pregnancy is different.

How do you calculate when you've conceived? ›

What is the date of conception? Conception usually occurs 11 to 21 days following the first day of the previous period in a woman who has regular menstruation. Most women do not know the precise day of conception because it is difficult to predict when ovulation will occur.

How do you calculate the month you were conceived? ›

Last Menstrual Period

Conception usually occurs around 11-21 days after the first day of the last period of a woman who has a regular period. The estimation of conception date is based on this, but is rarely ever exact since it is difficult to know exactly when ovulation occurs.

How many weeks after conception are you due? ›

Most pregnancies last around 40 weeks (or 38 weeks from conception), so typically the best way to estimate your due date is to count 40 weeks, or 280 days, from the first day of your last menstrual period (LMP).

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