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- Remember that pregnancy due date calculators can help you learn more about your estimated due date and pregnancy timeline, but they are not a replacement for medical advice. Our calculation is based on the last menstrual period date you logged and is estimated on the basis of a 28-day cycle. However, cycle lengths differ from person to person and can vary from month to month. As this method is affected by the regularity of your menstrual cycle, the due date predictor is not 100% accurate. You should always notify a health care professional that you are pregnant. An ultrasound will be needed to date your pregnancy accurately.
- Please note that Flo Health does not collect, process, or store any of the data that you enter while using these tools. All calculations are done exclusively in your browser. Flo Health does not have access to the results. All data will be permanently erased after leaving or closing the page.
Gestational age is the age of pregnancy and is counted from the first day of your LMP. So technically it includes two weeks during which you weren't pregnant yet.
At 4 weeks pregnant, your future baby has finally found his home for the next eight months. The blastocyst has arrived from a fallopian tube to your uterus. You can get a positive pregnancy test result at this stage.
By week 5, you should have missed your period, which is one of the most obvious sign you're expecting. Under the influence of hormonal changes, you can feel the first signs of pregnancy: breast swelling, fatigue, headache, and back pain.
Starting from pregnancy week 6, you may experience morning sickness. This is the result of hormonal changes occurring in your body. Malaise, breast swelling, darkening of the nipple areola, and frequent urination can bother you, too. In case of bleeding, you should consult your doctor.
At 7 weeks pregnant, symptoms start kicking in and your uterus almost doubles in size. Be prepared for a possible increase in nausea, fatigue, heartburn, and other pregnancy symptoms. Morning sickness may give a lot of trouble. Try to find some ways to cope with it.
At 8 weeks pregnant, you need to plan your first visit to the gynecologist. The doctor will prescribe the necessary tests and examinations for the first trimester of pregnancy. You may feel the growing discomfort of morning sickness. Try to be patient; it usually lasts until the 14th week only.
At 9 weeks pregnant, your baby is already about 0.6–0.7 in (16–18 mm) and weighs about 0.11 oz (3 g). The tail has disappeared; human features are becoming more distinct. The joints of his/her hands and legs can flex; the nipples and hair follicles are developing. Taste buds are beginning to form on the tongue, as well as primary tooth buds in the gums.
Week 10 of pregnancy is the time when almost all vital organs and tissues of your baby have formed. Now, they are beginning to function and grow rapidly. He or she can swallow amniotic fluid and move their arms and legs. The skin is getting covered with small hair and the fingers have tiny nails. Testes in boys already start to produce testosterone.
At 11 weeks pregnant, your baby has already reached 2 in (5 cm) in size. Now, his/her head is half the length of the body, but in the coming weeks, the body will grow enough to make up for it. The fetus skin is so thin and translucent that through it you can see an extensive network of vessels. Placental vessels are expanding to provide the fetus with necessary nutrients and oxygen.
At 12 weeks pregnant, your baby weighs about 0.49 oz (14 g). His/her vocal cords are forming, and kidneys are starting to produce urine, filling the bladder. Although you cannot feel it yet, you can see the baby during a sonogram screening (ultrasound).
Welcome to the last week of the first trimester! Most early pregnancy symptoms will soon be left behind. At 13 weeks pregnant, your baby is constantly growing. Now, he/she is more than 2.8 in (7 cm) from the top of his/her head to the coccyx.
At 14 weeks pregnant, your baby is developing rapidly. In a while, you will be able to feel them moving and kicking. Your body starts actively gaining weight. This occurs due to an increase in blood and lymph volume.
At 15 weeks pregnant, your baby your baby is actively drawing in amniotic fluid through his/her nose. Very soon you'll start looking pregnant indeed as your uterus has risen from your pelvic region to your lower abdomen. Time to plan pregnancy shopping!
You’re on week 16 of your pregnancy, and things are really starting to gear up! Your tiny baby is not so tiny anymore, and it most definitely looks like a human baby now. By week 16 of your pregnancy, you’re 4 months in. That means you’re nearly halfway there and only have 5 more months to go!
If you’ve been enjoying a relatively subtle pregnancy with very little belly to show for it, that’s probably over now! Your waist will gradually disappear as your uterus moves upwards and out of your pelvis.
If you’ve been astonished by your baby’s rapid growth and weight gain over the last few weeks, by week 18 this will start to level off a little — but there’s still lots of big news in your little one’s early life! At this stage, he or she can yawn, stretch, and even make facial expressions like frowning. The baby’s sense of taste is developing, and taste buds can now distinguish between sweet and bitter.
At 19 weeks pregnant, your rounded belly is very noticeable. The first hair appears on the baby's head, and the brain areas responsible for the senses — tactile, gustatory, olfactory, visual and auditory — are developing rapidly.
Congratulations! You are halfway to meeting your baby. The baby's legs have almost straightened, so from now on, he/she will be measured from head to toe.
As a 21 week pregnant woman, you have crossed the halfway line on your journey to becoming a mother. Your baby is getting bigger. You can now definitely feel her presence as she explores the real estate that you’ve prepared for her.
If you are entering the 22nd week of your pregnancy, without doubts it is getting crowded in there! Your baby is growing and invading your space. And your uterus stretches to about 2 cm (0.8 in) above your belly button to fit your growing baby.
For many women, being 23 weeks pregnant is an exciting time because you may finally be showing your baby bump! Among other things, your baby’s eyes and lips are taking shape. They will begin to gain weight more weight which will eventually fill out their wrinkly skin.
At 24 weeks pregnant, your baby is almost a foot long. You could be experiencing a tingling sensation in your joints, which is known as carpal tunnel syndrome. It is a common condition during pregnancy which occurs due to fluid build-up in your joints which results in compression of the median nerve.
Once you reach week 25 of your pregnancy, you’ll be nearing the end of your second trimester. It can feel like times flies! At 25 weeks pregnant, you’re approximately 5 months and 2 weeks along. Your baby has been growing steadily and even though it’s still not ready, it won’t be long before it comes into the world.
You’re likely to put on between 16 and 22 pounds by now. At one point during this week, your baby will open his or her eyes for the first time. He or she is not yet able to see anything inside of the uterus but will blink closing and opening his or her eyes when falling asleep and waking up.
The 27th week of the pregnancy marks the final two weeks of the second trimester. If your baby is more active at night you might suffer from insomnia and have trouble sleeping. Compensate for the lack of sleep time during the night by napping during the day more when the baby is sleeping.
At 28 weeks you are now entering the third trimester of your pregnancy. At this stage, your baby is pretty well-developed. Her organs, tissues, and nerves continue to grow, but she already has all of the systems necessary for survival outside the uterus. Towards the end of the pregnancy, babies start to recognize familiar sounds and voices.
At 29 weeks pregnant, you're likely to develop varicose veins like 40 percent of expectant moms. It's also a good time to start doing a kick count. Let your doctor or midwife know if you notice that your baby is becoming less active.
At 30 weeks pregnant, you are likely to experience shortness of breath. Your baby is still up high near your rib and is waiting a bit – it is soon expected to drop down into your pelvis.
At 31 weeks pregnant, your breasts can get leaky producing the first baby’s food – colostrum. This is one of the symptoms that your body is getting ready for the big day. You are likely to experience shortness of breath. This week your baby is going through major nerve and brain development.
At 32 weeks pregnant, your body may start flexing its muscles preparing for the big day. Your baby is also preparing for her debut mastering the skills she’ll need to thrive outside your womb: swallowing, breathing, sucking.
At 33 weeks pregnant, you may notice that your baby’s movements are affected by your daily routine. Your belly continues to grow and it’s getting even more troublesome to find a comfortable sitting or sleeping position.
At 34 weeks pregnant, your breasts could start leaking small amounts of yellowish colostrum. Your baby is already the size of a school bag and weighs as a melon. If you’re worried about your safety at work, time to talk to your employer about maternity benefits.
At 35 weeks pregnant, you may know how your baby’s moving in your womb just by looking at your bump. It can you give you some discomfort and make you a bit breathless. At this point, many moms can’t wait for the baby to get here, while others are feeling a bit anxious about giving birth. Both feelings are completely normal!
At 36 weeks pregnant, your baby is sleeping between 60 and 80% of the time. It has finally moved into your pelvic cavity, the pressure on your diaphragm is released, and lightening happens. Your baby can now open its eyes, suck its thumb, breathe, and recognize voices!
Welcome to your 37th week of pregnancy, and congratulations! The baby moves further into the pelvis. It is considered to be ‘at-term’ and can actually arrive any day now. Make sure you are ready for the arrival of a new family member.
At 38 weeks pregnant, you can find yourself spending the whole life peeing. The pressure on your bladder is tremendous. Your baby is a fully functioning little human and your placenta is fully grown.
Welcome to the week 39 of pregnancy! Your baby is full term, meaning that it is fully developed and is only waiting for the right time to make an entrance into the world. Have you prepared everything that is needed to welcome your baby?
At 40 weeks pregnant, you may feel disappointed that your due date has come and gone. Don’t panic and make the last preparations for a new human who’ll soon join the world.
At week 41 of pregnancy, you might be dying out of the desire to give birth and see your baby. But rest assured that plenty of moms-to-be go past their due date and everything turns out just fine.
When a pregnancy lasts for 42 weeks or more it is referred to as a post-term pregnancy. While not many studies exist that prove why some women’s pregnancy lasts for 42 weeks, medical experts believe that factors such as hormones, genetics, and even obesity can be the cause.
Whether you’ve been trying for a baby or not, there can be a lot of questions that surround pregnancy, like when is your fertile window? When should you take a pregnancy test to get the most accurate result? And what are the earliest signs of pregnancy? At Flo, we want to demystify this time.
If you’ve taken a pregnancy test and got a positive result, you might have tried to do the mental math to determine when your due date is. That’s where Flo’s pregnancy due date calculator comes in.
While it’s impossible to predict your due date with 100% accuracy, Flo uses some basic information about your last period to help you figure out your estimated due date (EDD). This information isn’t only useful once you’re pregnant. You might also want to get a better idea of due date timings before you start trying to conceive to plan out your pregnancy (as much as you can).
If you’re not quite sure where to start with our estimated due date calculator, then scroll down for a guide on how to use it, plus more information on how due dates (and pregnancy) are calculated, when you could have conceived, and how far along you might be.
Note:
- If you’ve already had your first ultrasound scan, you can use our ultrasound due date calculator instead.
- Or, if you’ve conceived through egg retrieval and in vitro fertilization (IVF), you can use our IVF due date calculator.
Key takeaways about using a due date calculator
- There are lots of different ways that you can figure out your due date. Generally, you’ll need to know the first day of your last menstrual period (LMP) or IVF transfer date. Most pregnancies last around 40 weeks from the last day of your menstrual period. However, this can differ. Keep reading to find out more.
- It can feel like a really exciting milestone to have a date in your mind that you’ll meet your baby, but due dates are just estimates, and birth may happen a few weeks before or after.
- Your doctor will use your estimated due date to guide the prenatal care you receive and determine the timing of tests and treatments during pregnancy.
- While using a pregnancy due date calculator can be fun and useful, it isn’t a substitute for medical advice. Always confirm your due date with your doctor.
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How is my due date calculated?
So, first things first, how do pregnancy due date calculators work, and how will your doctor estimate your due date? Dr. Sara Twogood, obstetrician and gynecologist, Cedars-Sinai Medical Group, California, US, explains that there are a few different ways you can do this.
Many doctors will use your cycle data, so using a period-tracking app like Flo may help you in your appointments. You’ll have the dates of your last period right in your pocket alongside any symptoms you experienced in the run-up to getting pregnant.
First day of your last menstrual period
Many due date calculators (including Flo’s) use your LMP. You might be curious why the date of your last period can tell you so much. The answer is pretty straightforward: Knowing exactly when you conceive is really difficult.
You can get pregnant several days after you’ve had unprotected sex. Sperm can live in your body for up to five days, an egg can be fertilized for up to 24 hours after its release from the ovary, and ovulation doesn’t always happen on the same day each month. You can find out when you’re likely to be ovulating each month using our online ovulation calculator. Your fertile window includes the five days leading up to ovulation and one day afterward. So knowing the exact date you conceived is hard.
This is why doctors often use your LMP to estimate your due date. It’s usually known and makes the math reasonably straightforward. This is the most commonly used method health care professionals use to predict a due date. Here’s how it works:
Step 1: Start with the first day of your last menstrual period. If you’re using a period-tracking app like Flo, you’ll know when your last period was — and the date it started.
Step 2: Add 40 weeks to this date (or 280 days). This assumes a typical 28-day cycle, with ovulation occurring around day 14.
Example: If your LMP was January 1, you add 280 days to get a due date around October 8.
It’s worth noting that this rule relies on your cycle being very typical — 28 days long. However, everyone’s cycle is slightly different. Yours may vary from month to month and as you progress through life. It’s actually typical for a person’s cycle to vary in length from anywhere between 21 and 35 days. If your cycle lasts longer, the estimated due date will likely be later. If you have a shorter cycle, your due date may be earlier.
This may feel like a lot of math, so to be absolutely sure about your due date, it’s best to speak to your doctor.
At a glance, what month am I due?
Predicting your due date isn’t an exact science. However, assuming that you’re pregnant for 40 weeks and you have an average, regular cycle of 28 days…
- If you conceived in January, your baby may be due in October
- If you conceived in February, your baby may be due in November
- If you conceived in March, your baby may be due in December
- If you conceived in April, your baby may be due in January
- If you conceived in May, your baby may be due in February
- If you conceived in June, your baby may be due in March
- If you conceived in July, your baby may be due in April
- If you conceived in August, your baby may be due in May
- If you conceived in September, your baby may be due in June
- If you conceived in October, your baby may be due in July
- If you conceived in November, your baby may be due in August
- If you conceived in December, your baby may be due in September
Your due date can feel definite but Dr. Twogood explains that it’s more of an estimate of when your baby might arrive. Yours may vary depending on the length of your cycle and at what point in the month that you conceived.
Similarly, studies have highlighted that very few births actually happen on their due date and while the average pregnancy is 40 weeks, the American College of Obstetricians and Gynecologists outlines it’s quite typical to give birth between 37 weeks and 42 weeks. Your baby may come a little early or a couple of weeks later pushing you into a different month.
If you’d like a more accurate estimation of when your baby may be due you can use the calculator above. And if your cycles are irregular your doctor may work out your due date using different information.
Other ways of calculating your due date
If your cycle is irregular or you conceived using IVF, then using your period dates may not be appropriate for you. There are other methods that you can use to try to figure out your estimated due date.
Date of conception
If your cycle runs like clockwork, and you were having sex to get pregnant at a specific time, then you might have an inkling that conception happened on a certain date. This could be the case if you’ve been tracking your ovulation using an ovulation-tracking app like Flo. But it’s not always the most accurate method to figure your due date, says Dr. Twogood.
As we’ve already mentioned, knowing your conception date accurately can be really hard. Your fertile window includes the five days leading up to ovulation and one day afterward, and it’s not possible to know exactly when you conceived in that period. You can find out when you’re likely to be ovulating each month using our online ovulation calculator.
“Even if a pregnant patient only had sex on one day, the dating of that pregnancy would still rely on other methods beyond that day to confirm the best due date,” Dr. Twogood reveals.
IVF transfer date
If you’ve had in vitro fertilization, then your baby’s due date is calculated slightly differently.
The good news is that IVF due dates are generally more accurate because you’ll know exactly when you had your embryo transferred or medically conceived. Once your eggs have been fertilized, they’ll be transferred back into your body after three or five days. This gives the fertilized egg a few days to start to develop before being implanted.
Using the date of your LMP and your transfer date, your doctor will be able to establish if you’re either two weeks and three days pregnant or two weeks and five days pregnant on the day of your transfer and will be able to calculate your IVF due date from that. However, no due date is 100% accurate. Use our IVF due date calculator to figure out when you could be due.
First ultrasound
Your first ultrasound scan appointment can feel like a real milestone in pregnancy. When you first find out you’re pregnant, your doctor may have given you an estimated due date based on your last period date. Your doctor will then use this scan to check that your due date and gestational age (how far along in pregnancy you are) are correct. Think of it as them confirming earlier estimations.
This is especially important if your period doesn’t always arrive at the same time each month. “For patients with longer or shorter cycles or irregular periods, we often will use an early ultrasound to estimate the due date rather than the LMP,” explains Dr. Twogood.
The ultrasound measures your embryo’s size, from the crown, which is the top of the head, to the rump, which is the end of their bottom. This helps your doctor estimate gestational age.
If you’ve already had your first ultrasound scan and want to know more, you can use our ultrasound due date calculator.
How accurate is a pregnancy due date?
There’s a lot to take in when you first find out you’re pregnant, and your due date can feel like the first bit of firm news. However, Dr. Twogood explains, “I always remind patients that even though it’s called a due date, that is not the day the baby is due! It’s an estimate to determine maturity and approximate timing of delivery. It is common and normal to deliver up to three weeks before the due date and one to two weeks after.”
Can a pregnancy due date change?
Lots of people will calculate their due date as one of the first things they do after finding out they’re pregnant. It can be useful for having a rough idea of when your baby will arrive and can feel exciting. However, you should always confirm your due date with your doctor, and once you have your EDD, it isn’t a guarantee that your baby will come on that day.
The significance of a due date for prenatal care
According to Dr. Twogood, understanding your due date can help you and your doctor plan the phases of your pregnancy, expected milestones, and when to arrange medical checkups. “Knowing your due date and therefore the gestational age of your pregnancy helps guide optimal prenatal care,” she says.
For example, she explains, the recommended time to screen for gestational diabetes is between 24 and 28 weeks of pregnancy. If the test is done before 24 weeks or after 28 weeks, the results might not be as accurate for diagnosing or ruling out gestational diabetes.
Knowing your due date and gestational age also helps you and your doctor set expectations when a pregnancy is high risk, she adds. “Especially in the case of preterm birth, to use an extreme example, knowing if a baby will be 24 weeks or 28 weeks at the time of birth is a big difference!”
You can use a pregnancy-tracking app like Flo to follow the ways your baby and body change every week of pregnancy and to give you hints and tips on what you might expect.
Frequently asked questions about pregnancy due date calculators
Where can I find a due date calculator for pregnancy?
You can find pregnancy due date calculators on several trusted health and medical websites, including this one. Our pregnancy due date calculator can help you figure out your estimated due date or when your baby might arrive. But remember that pregnancy due date calculators are not a replacement for medical advice. You should always notify your doctor when you’re pregnant.
How can I calculate the due date based on the conception date?
If you know your exact conception date (maybe because you tracked your ovulation using an app like Flo), your due date can be estimated by adding 38 weeks. It’s the same method as using your last menstrual period, you just skip the first two weeks before ovulation. However, as we’ve already said, knowing exactly when you conceived can be really tough, as your fertile window lasts around six days, and you could have conceived at any time during that window.
Try some of Flo’s other online tools, including our hCG calculator, our pregnancy test calculator, and our period calculator.
References
Bahtiyar, Mert Ozan, and Carole Gravino. “Atlas of Selected Normal Images.” Obstetric Imaging: Fetal Diagnosis and Care, Elsevier, 2018.
“Calculating a Due Date.” Johns Hopkins Medicine, www.hopkinsmedicine.org/health/wellness-and-prevention/calculating-a-due-date. Accessed 25 Oct. 2024.
Choe, Jennifer, and Anthony L. Shanks. “In Vitro Fertilization.” StatPearls, StatPearls Publishing, 4 Sep. 2023, www.ncbi.nlm.nih.gov/books/NBK562266/.
“Due Date Calculator.” Cleveland Clinic, my.clevelandclinic.org/health/diagnostics/22052-due-date-calculator. Accessed 24 Oct. 2024.
“Gestational Age.” MedlinePlus, medlineplus.gov/ency/article/002367.htm. Accessed 24 Oct. 2024.
“Gestational Diabetes.” Mayo Clinic, 9 Apr. 2022, www.mayoclinic.org/diseases-conditions/gestational-diabetes/diagnosis-treatment/drc-20355345.
“Irregular Periods.” Cleveland Clinic, my.clevelandclinic.org/health/diseases/14633-abnormal-menstruation-periods. Accessed 24 Oct. 2024.
“Menstrual Cycle.” Cleveland Clinic, my.clevelandclinic.org/health/articles/10132-menstrual-cycle. Accessed 24 Oct. 2024.
“Pregnancy: Identifying Fertile Days.” MedlinePlus, medlineplus.gov/ency/article/007015.htm. Accessed 24 Oct. 2024.
“Preterm Labor and Birth.” The American College of Obstetricians and Gynecologists, Apr. 2023, www.acog.org/womens-health/faqs/preterm-labor-and-birth.
“Sperm: How Long Do They Live after Ejaculation?” Mayo Clinic, 5 May 2022, www.mayoclinic.org/healthy-lifestyle/getting-pregnant/expert-answers/pregnancy/faq-20058504.
Witt, Barry. “Trying to Get Pregnant? Here’s When to Have Sex.” The American College of Obstetricians and Gynecologists, Aug. 2023, www.acog.org/womens-health/experts-and-stories/the-latest/trying-to-get-pregnant-heres-when-to-have-sex.
“Ultrasound Exams.” The American College of Obstetricians and Gynecologists, June 2017, www.acog.org/womens-health/faqs/ultrasound-exams.
History of updates
Current version (10 February 2025)
Published (03 April 2019)
In this article
Understand what your symptoms might mean — and what's normal for you — by tracking your cycle.
Follow your baby's growth and see how your body is changing.
Know when you're most fertile to maximize your chances of getting pregnant.
