Pregnancy calculator: A week-by-week pregnancy calendar (2024)

Updated 29 September 2023 |

Published 08 September 2023

Pregnancy calculator: A week-by-week pregnancy calendar (1)

Medically reviewed by Dr. Sara Twogood, Obstetrician and gynecologist, Cedars-Sinai Medical Group, California, US

Written by Sarah Biddlecombe

Your pregnancy

Month

Trimester

Track your pregnancy

First-trimester

Second-trimester

Third-trimester

1 1 week pregnant 2 2 weeks pregnant 3 3 weeks pregnant 4 4 weeks pregnant 5 5 weeks pregnant 6 6 weeks pregnant 7 7 weeks pregnant 8 8 weeks pregnant 9 9 weeks pregnant 10 10 weeks pregnant 11 11 weeks pregnant 12 12 weeks pregnant 13 13 weeks pregnant 14 14 weeks pregnant 15 15 weeks pregnant 16 16 weeks pregnant 17 17 weeks pregnant 18 18 weeks pregnant 19 19 weeks pregnant 20 20 weeks pregnant 21 21 weeks pregnant 22 22 weeks pregnant 23 23 weeks pregnant 24 24 weeks pregnant 25 25 weeks pregnant 26 26 weeks pregnant 27 27 weeks pregnant 28 28 weeks pregnant 29 29 weeks pregnant 30 30 weeks pregnant 31 31 weeks pregnant 32 32 weeks pregnant 33 33 weeks pregnant 34 34 weeks pregnant 35 35 weeks pregnant 36 36 weeks pregnant 37 37 weeks pregnant 38 38 weeks pregnant 39 39 weeks pregnant 40 40 weeks pregnant 41 41 weeks pregnant 42 42 weeks pregnant

As you track pregnancy, you probably know how many weeks you are, but what about how many months? You might also be curious to know how far along in your pregnancy you are so you know how long it’s likely to be before you get to meet your baby for the first time.

This is where our pregnancy calculator comes in handy. Keep reading to learn more about how to use it, along with some expert pregnancy advice from Dr. Renita White, obstetrician and gynecologist, Georgia, US.

  • 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.
  • Our Pregnancy Calculator is based on a 40-week pregnancy. As we cannot know when exactly your baby will be born, the calculator is not 100% accurate.
  • Remember that pregnancy calculators, pregnancy due date calculators, and birth date calculators can help you learn more about your estimated due date and pregnancy time line, but they are not a replacement for medical advice. You should always notify your health care provider that you are pregnant. An ultrasound will be needed to date your pregnancy.
Pregnancy calculator: A week-by-week pregnancy calendar (2)

How to use our pregnancy calculator

Our pregnancy calculator uses some basic information to figure out how far along you are. All you need to do is input how many weeks and days pregnant you are, and the tool will do the rest.

Once you enter the data, you will get a personalized overview of your pregnancy in months so far. This will include a percentage of how far along you are, how many months pregnant you are, and which trimester you’re in. You’ll also be able to click through to an in-depth article that will tell you about what’s happening during that specific week of your pregnancy. Plus, if you’d like an idea of when your due date is likely to fall, you can use our due date calculator, too. Additionally, you can check out our implantation calculator to find out when the implantation might have occured. Clever, huh?

Week-by-week calendar

Pregnancy is an exciting time filled with lots of change — for both your growing baby and your growing body, so you’ll no doubt have lots of questions. Those questions might include: What developmental milestones happen as the weeks go on? What symptoms can you expect and when? And what things should you be thinking about each step of the way? We’ve spoken to Flo experts to bring you the essential knowledge you need for your pregnancy, week by week. Simply scroll through our carousel below to find your week of pregnancy and learn more.

What is a trimester?

First up, let’s go over the basics. What exactly is a trimester? “A trimester represents the three sections of time periods of pregnancy,” explains Dr. White. “These periods represent the 1st, 2nd, and 3rd trimesters [up until you give birth].”

How many weeks are in each trimester?

Counting from your last menstrual period, there are 13 complete weeks in the 1st trimester and 14 complete weeks in the 2nd trimester. The amount of weeks in your 3rd trimester will vary depending on when your baby is born, so if you’re wondering how long a pregnancy lasts, there’s no specific answer. Your due date marks 40 weeks of pregnancy (or 9.2 months!), but it’s common for your baby to be born on a different date. In fact, only around 5% of babies are actually born on their due date.

You might also be wondering why your health care provider is counting your pregnancy in weeks rather than in months or even just trimesters. Over to Dr. White. “Many things can change rapidly in a pregnancy, even week by week,” she explains. “Also, some tests and evaluations are needed at specific weeks of pregnancy. So for more precise management and observation, it is better to evaluate pregnancy by week.”

Pregnancy calculator: A week-by-week pregnancy calendar (3)

Tips on having a healthy pregnancy

Having a healthy pregnancy not only helps to support your baby as it develops, but it also helps to support your body as it adjusts to all the changes that pregnancy can bring. But what are some essential do’s and don’ts to consider when planning a healthy pregnancy?

Do have a healthy pregnancy diet

When it comes to a healthy pregnancy diet, there are a few things to consider. First of all, the usual healthy eating principles are the same in pregnancy as they are at other times — it’s good to eat a balanced diet with lots of fruits, veggies, lean protein, healthy fats, and whole grains. However, there are some foods you need to avoid, including foods made from unpasteurized milk and raw or undercooked meats, because of the risk of bacteria and sickness. You can find out more in our guide to a healthy pregnancy diet.

Do get the right nutrients

Alongside a healthy diet, you might also be considering taking a pregnancy supplement to help you get all of the nutrients that both you and your growing baby need. One of the most important nutrients is folic acid. Experts recommend you get 600 micrograms per day during pregnancy; you should be able to get some of this from your diet, and you’ll need to take a daily supplement containing at least 400 micrograms of folic acid. But why? “Folic acid is very important in brain and spine development of the baby,” explains Dr. White. “Most importantly, it is vital for the development of the neural tube. The neural tube is part of the early central nervous system.”

Other recommended nutrients include:

  • Iron
  • Calcium
  • Choline
  • Vitamin D
  • Omega-3 fatty acids
  • B vitamins
  • Vitamin C

Always speak to your health care provider before taking any new supplements.

Do keep exercising

Pregnant women are advised to do around 150 minutes of moderate-intensity exercise each week. And, if you feel able to, keeping up with a healthy workout routine can have many benefits. “Exercises can help with alleviating common pregnancy-related pains, including back and joint pain,” explains Dr. White. “It can help you maintain a healthy pregnancy weight. It has also been shown to decrease the risk of gestational diabetes and shorten your length of labor.”

If you were active before your pregnancy, it’s probably a good idea to decrease the intensity of your workouts. If you weren’t active, experts advise that you start slow when it comes to introducing exercise into your pregnancy routine. It’s also a good idea to avoid any contact sports or workouts that involve any risk of falling to help keep your baby safe and protected. It’s always a good idea to ask your doctor any questions you have about exercising safely during pregnancy.

Don’t smoke, take drugs, or drink alcohol

“Smoking cigarettes and illicit drug use should absolutely be avoided in pregnancy,” says Dr. White. “It can have a negative impact on a baby’s development as well as the development of the placenta. This can lead to fetal growth restrictions, preterm labor, and placental abruption (where the placenta detaches early before the baby is ready to be born).”

She adds that: “Alcohol use also has the potential to impact a baby’s development. Since we don’t know how much alcohol it takes to negatively impact a baby, we recommend avoiding it altogether.”

Of course, these tips aren’t the only things to consider when planning a healthy pregnancy, but they’re a good place to start. Remember to always chat with your health care provider for tailored advice that’s specific to your own pregnancy. You’ve got this!

FAQs

Can you show at 4 weeks pregnant?

As exciting (and reassuring) as it can be to start showing a baby bump, you’re unlikely to have a pregnancy belly at 4 weeks. You could start showing around 12 weeks pregnant, although every pregnancy (and every pregnant belly) is different, so try not to compare yourself to others.

What week does my baby’s sex develop?

Your baby will have an assigned sex from the moment of conception, when the embryo will have either an XX chromosome (female) or XY chromosome (male). If you opt for noninvasive prenatal testing, those results can also show you the sex of your baby (if you choose to find out, of course!). The testing can be done as early as 10 weeks pregnant, so you could find out by around 12 weeks pregnant.

Should I still be cramping at 5 weeks pregnant?

Rest assured that cramping that feels a little like period pain is a perfectly normal symptom to experience at 5 weeks pregnant. However, if the cramps become extremely painful, are accompanied by bleeding, or if you have any concerns, always reach out to your health care provider right away.

Is 33 weeks safe to deliver?

Babies born at 33 weeks pregnant are considered to be moderate to late preterm, and they have a good chance of survival. However, they’re likely to need extra care, such as in a neonatal unit. This can sound frightening, but rest assured that only 6% to 7% of babies are born between 32 and 36 weeks.

Is 7 weeks too early for an ultrasound?

No, 7 weeks isn’t necessarily too early for an ultrasound. The timing of your first ultrasound will depend on your health care provider, but it could indeed be as early as 7 or 8 weeks pregnant. Other providers might not offer an ultrasound until closer to 12 weeks pregnant.

What is the last organ to develop in a fetus?

Good question! All of your baby’s organs will be formed by 12 weeks pregnant, but they’ll continue to develop at various stages throughout your pregnancy. Your baby’s lungs are the last organs to fully develop at around 36 weeks pregnant.

References

Ananth, C. V., et al. “Maternal Cigarette Smoking as a Risk Factor for Placental Abruption, Placenta Previa, and Uterine Bleeding in Pregnancy.” American Journal of Epidemiology, vol. 144, no. 9, Nov. 1996, pp. 881–89, doi:10.1093/oxfordjournals.aje.a009022.

Artal-Mittelmark, Raul. “Stages of Development of the Fetus.” MSD Manual Consumer Version, Sep. 2022, www.msdmanuals.com/en-gb/home/women-s-health-issues/normal-pregnancy/stages-of-development-of-the-fetus.

“Fetal Development.” Cleveland Clinic, my.clevelandclinic.org/health/articles/7247-fetal-development-stages-of-growth. Accessed 30 Aug. 2023.

Field, David, et al. “Chapter 3, The Late And Moderately Preterm Birth Study.” Towards Reducing Variations in Infant Mortality and Morbidity: A Population-Based Approach. NIHR Journals Library, 2016, www.ncbi.nlm.nih.gov/books/NBK349423/.

“Foods to Avoid in Pregnancy.” NHS, www.nhs.uk/pregnancy/keeping-well/foods-to-avoid/. Accessed 30 Aug. 2023.

“Health Tips for Pregnant Women.” National Institute of Diabetes and Digestive and Kidney Diseases, www.niddk.nih.gov/health-information/weight-management/healthy-eating-physical-activity-for-life/health-tips-for-pregnant-women. Accessed 30 Aug. 2023.

“How Your Baby Develops Week to Week.” NHS Inform, 25 Jan. 2023, www.nhsinform.scot/ready-steady-baby/pregnancy/your-baby-s-development/how-your-baby-develops-week-to-week.

“How Your Fetus Grows during Pregnancy.” The American College of Obstetricians and Gynecologists, Aug. 2020, www.acog.org/womens-health/faqs/how-your-fetus-grows-during-pregnancy.

Khambalia, Amina Z., et al. “Predicting Date of Birth and Examining the Best Time to Date a Pregnancy.” International Journal of Gynaecology and Obstetrics, vol. 123, no. 2, Nov. 2013, pp. 105–09, doi: 10.1016/j.ijgo.2013.05.007.

Khoshnood Shariati, Maryam, et al. “Perinatal Complications Associated with Preterm Deliveries at 24 to 33 Weeks and 6 Days Gestation (2011- 2012): A Hospital-Based Retrospective Study.” Iranian Journal of Reproductive Medicine, vol. 13, no. 11, Nov. 2015, pp. 697–702, www.bioline.org.br/pdf?rm15089.

“NIPT Test.” Cleveland Clinic, my.clevelandclinic.org/health/diagnostics/21050-nipt-test. Accessed 30 Aug. 2023.

“Nutrition during Pregnancy.” The American College of Obstetricians and Gynecologists, June 2023, www.acog.org/womens-health/faqs/nutrition-during-pregnancy.

“Overdue Pregnancy: What to Do When Baby’s Overdue.” Mayo Clinic, 27 July 2022, www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/overdue-pregnancy/art-20048287.

“Pregnancy Diet: Focus on These Essential Nutrients.” Mayo Clinic, 18 Feb. 2022, www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/pregnancy-nutrition/art-20045082.

“Preterm Birth.” World Health Organization, 10 May 2023, www.who.int/news-room/fact-sheets/detail/preterm-birth.

“Stomach Pain in Pregnancy.” NHS, www.nhs.uk/pregnancy/related-conditions/common-symptoms/stomach-pain/. Accessed 30 Aug. 2023.

“Substance Use during Pregnancy.” Centers for Disease Control and Prevention, www.cdc.gov/reproductivehealth/maternalinfanthealth/substance-abuse/substance-abuse-during-pregnancy.htm. Accessed 30 Aug. 2023.

“Ultrasound in Pregnancy: What to Expect, Purpose, and Results.” Cleveland Clinic, my.clevelandclinic.org/health/diagnostics/9704-ultrasound-in-pregnancy. Accessed 30 Aug. 2023.

Vij, Sarah. “Can You Choose the Sex of Your Baby?” Cleveland Clinic, 7 July 2023, health.clevelandclinic.org/boy-or-girl-can-you-choose-your-babys-sex/.

“You and Your Baby at 36 Weeks Pregnant.” NHS, www.nhs.uk/pregnancy/week-by-week/28-to-40-plus/36-weeks/. Accessed 30 Aug. 2023.

Zanotti, Salena. “How to Exercise Safely if You’re Pregnant.” Cleveland Clinic, 23 Nov. 2022, health.clevelandclinic.org/pregnancy-safe-workouts/.

“Week 5.” NHS, www.nhs.uk/start-for-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-5/. Accessed 30 Aug. 2023.

“Week 12.” NHS, www.nhs.uk/start-for-life/pregnancy/week-by-week-guide-to-pregnancy/1st-trimester/week-12/. Accessed 30 Aug. 2023.

History of updates

Current version (29 September 2023)

Medically reviewed by Dr. Sara Twogood, Obstetrician and gynecologist, Cedars-Sinai Medical Group, California, US

Written by Sarah Biddlecombe

Published (08 September 2023)

Pregnancy calculator: A week-by-week pregnancy calendar (2024)

FAQs

How to calculate pregnancy week by week? ›

To calculate your pregnancy weeks, just count from the first day of your last period to the current date in weeks. That way you will get how many weeks of pregnancy is over. How does the pregnancy due date calculator work? Add 280 days (40 weeks) to the first day of your last menstrual period (assuming a 28-day cycle).

How do you count pregnancy weeks on a calendar? ›

Your EDD is 40 weeks from the first day of your last menstrual period (LMP). It's important to remember that your due date is only an estimate — most babies are born between 38 and 42 weeks from the first day of their mom's LMP and only a small percentage of women actually deliver on their due date.

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.

How can I confirm how many weeks pregnant I am? ›

Ultrasound: At some point during your pregnancy, you will likely have an ultrasound scan. This enables your healthcare provider to check on fetal growth and monitor other development milestones; it also provides the most accurate estimate for how many weeks pregnant you are and what your due date will be.

What is the most critical week of pregnancy? ›

In general, major birth defects of the body and internal organs are more likely to happen between 3 to 12 embryonic/fetal weeks. This is the same as 5 to 14 gestational weeks (weeks since the first day of your last period). This is also referred to as the first trimester.

How do you count a baby by weeks? ›

How to Count Pregnancy Weeks. The basic formula is LMP + 280 days = EDD (estimated due date), and pregnancy week counting starts on the first day of your last period, starting with Week 0 (not 1!) and counting all the way up to Week 40 (your due date) and as high as Week 42.

How do doctors calculate pregnancy weeks? ›

Contrary to popular belief, pregnancy does not start at conception. So, when does pregnancy start counting? The pregnancy timeline actually starts on the first day of your last menstrual period (LMP). This means that pregnancy actually ends up being 40 weeks or 10 months long!

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 calendar weeks are calculated? ›

A week is defined as an interval of exactly seven days, so that, except when passing through daylight saving time transitions or leap seconds, 1 week = 7 days = 168 hours = 10,080 minutes = 604,800 seconds. With respect to the Gregorian calendar: 1 Gregorian calendar year = 52 weeks + 1 day (2 days in a leap year)

Does 5 weeks pregnant mean 3 weeks? ›

In week 5 of pregnancy, your baby is actually 3 weeks old and has finally "moved into" your uterus. Read on to discover when it is worth taking a pregnancy test, why your little one now looks like a little UFO, and other things that still need to happen at the start of the first trimester.

How do I know the exact date I got pregnant? ›

Conception usually occurs 11 to 21 days following the first day of the previous period in a woman who has regular menstruation.

How am I 3 weeks pregnant if I conceived 2 weeks ago? ›

You might not be—here's why. Most OBs count pregnancy starting from the first day of your last menstrual period (LMP). (It's more accurate for doctors to estimate a due date this way.) So if you think you conceived about two weeks ago, you're probably at least four weeks pregnant—maybe even five.

How do I calculate exact pregnancy week? ›

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.

How to count the first week of pregnancy? ›

Pregnancy week 1

This first week is actually your menstrual period. Because your expected birth or due date (EDD or EDB) is calculated from the first day of your last period, this week counts as part of your 40-week pregnancy, even though your baby hasn't been conceived yet.

How far into pregnancy do you start showing? ›

Typically, your bump becomes noticeable during your second trimester. Between 16-20 weeks, your body will start showing your baby's growth. For some women, their bump may not be noticeable until the end of the second trimester and even into the third trimester. The second trimester starts in the fourth month.

How do you calculate how many weeks a baby is? ›

While in an ordinary year which is not a leap year, the number of weeks is 52 plus one day ( 365 / 7 = 52 weeks + 1 days ), leap years contain 52 weeks plus two days ( 366 / 7 = 52 weeks + 2 days ).

How do you calculate the number of weeks? ›

To calculate the number of weeks between two dates, start by counting the number of days between the start and end date. Then, divide that number by 7 days per week.

How to calculate how many weeks pregnant based on conception date? ›

If you happen to know the day you conceived, you can count 38 weeks from that day to find your due date. (Human gestation takes about 38 weeks.) But very few expectant moms know exactly when they conceived.

How do you convert pregnancy weeks? ›

Since many people don't know they're pregnant during the first few weeks, month one is extended to six weeks.
  1. Month 1: Week 1 through week 6.
  2. Month 2: Week 7 through week 11.
  3. Month 3: Week 12 through week 16.
  4. Month 4: Week 17 through week 20.
  5. Month 5: Week 21 through week 24.
  6. Month 6: Week 25 through week 28.
Apr 12, 2024

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