Health & Fitness Calculators
Due Date Calculator

Due Date Calculator

This online due date calculator helps moms-to-be calculate their due date based on their last menstrual period or the date of conception.

There was an error with your calculation.

You probably are not pregnant yet.

Table of Contents

  1. Here's Why You Should Use the Due Date Calculator
  2. The Length of a Pregnancy
  3. Gestational (Menstrual) Age vs. Fertile (Ovulation) Age
  4. Ways to Estimate Your Delivery Date
    1. Checking hCG Levels
    2. Date of Last Menstruation
    3. Ultrasound Scan
    4. Fetal Movement
    5. IVF Date
    6. Gynecological Examination
  5. Signs Labor is Imminent

Due Date Calculator

Did you just receive a positive pregnancy test and wonder when your baby is due? No worries! Our due date calculator can help you plan when to expect your new bundle of joy. You can calculate the due date by using the date you got pregnant or the date of your last menstrual period.

Knowing when your baby is due is fundamental to ensuring that you and your unborn child receive the best care for your needs. Just keep in mind that the due date calculator is only meant to provide you with an estimate. It's common for due dates to change and babies to come on different days.

Here's Why You Should Use the Due Date Calculator

A due date calculator serves one simple purpose: to give you an idea of when your baby may be born. This is especially helpful for women who may not have been to their gynecologist yet and would like to know their due date before seeing a doctor. But, as we mentioned, the pregnancy calculator is just an estimate, as very few babies are actually born on the day they are due.

There are several crucial reasons you'd want to know your due date. Aside from helping you plan and prepare for the baby's arrival, it also gives your care provider essential information needed to monitor the health of you and your growing baby.

Due dates can be calculated using several methods. However, some others aren't as accurate. When you visit your healthcare provider, they may change the date based on ultrasound measurements and the date of your last period.

The Length of a Pregnancy

Pregnancy is counted using the date of the first day of your last menses. This means that the two weeks leading up to you becoming pregnant are still counted. A full-term pregnancy spans about 40 weeks from the last menstrual period, which equates to roughly nine calendar months.

And with pregnancy, every week counts! Premature or preterm babies are those born at or before 37 weeks, and children born before 38 weeks are more likely to be admitted to the neonatal intensive care unit.

Gestational (Menstrual) Age vs. Fertile (Ovulation) Age

The most common way to estimate your due date is by calculating it using the date that your last menstrual period began. The due date is 40 weeks after that day. The benefit of this method is that most women know the day their last period started, as this is much more common than knowing when you ovulated. However, it may not be accurate, especially if your menstrual cycle is irregular, or you take birth control.

The ovulation age is used when the woman knows exactly what day she conceived. If you know this date, you simply count ahead 38 weeks, and that's your due date. This method is less common because it only works if you're positive about the day you got pregnant. It also works well for women who used an ovulation calculator to predict when they were ovulating.

It's also worth noting that it can be challenging to determine when the pregnancy occurred, even with an ovulation date. Sperm can live inside a woman's fallopian tubes for up to five days, but there's only a 12 to 24-hour window where you can get pregnant after ovulation. So, if you ovulated a couple of days after you had sex, the pregnancy may have occurred then.

Ways to Estimate Your Delivery Date

There are several ways your midwife or doctor can come up with an estimated delivery date. Let's take a look at each method and explain how they work:

Checking hCG Levels

HCG (Human chorionic gonadotropin) is commonly referred to as the pregnancy hormone because it's created by cells present in the placenta, which works to nourish the egg after it's fertilized and attached to the uterus. Levels of hCG can be detected in a urine test between 12 and 14 days after conception, while they can be found in the blood within 11 days.

Home pregnancy tests rely on the presence of hCG in your urine to produce a positive result. Doctors can perform blood tests to confirm pregnancy by using these levels before having the woman undergo an ultrasound.

Date of Last Menstruation

After you've received a positive pregnancy test, the most common way to calculate your due date is by using the date of your last period. You can input this data into the pregnancy due date calculator, or add 7 days to that date and subtract 3 months. Or, a simpler version of the equation is to add 40 weeks to the first day of your last menstrual period.

Ultrasound Scan

If doctors cannot predict your due date using other methods, they may turn to the help of an ultrasound machine. These tests are highly effective for determining how long you've been pregnant, especially when done before 20 weeks of pregnancy.

Up to the 7th week, you can calculate the gestational age using ultrasound as accurately as possible based on the size of the fetus. During this period, the embryo develops equally in all women.

From about the 10th week onward, fetal size will depend on many factors, including the weight of the parents, the woman's diet and genetic characteristics. These factors allow normally developing babies, at the same intrauterine stage of development, to have different sizes and weights.

Beginning at the 12th week, gestational age is determined by fetometry. Fetometry is a method of ultrasound measurement of the fetus by the size of arms, legs, head and internal organs.

In addition to the gestational age, fetometry can be used to determine:

  • The presence/absence of abnormalities in the fetus;
  • Signs of fetal retardation.
  • Genetic abnormalities.

After the 23rd week, fetometry findings become less reliable. Doctors use other methods to determine the gestational age and monitor fetal development.

Fetal Movement

Women typically feel their first baby's movements between 18 and 25 weeks of pregnancy, though experienced mothers may notice them earlier. Feeling the baby move is a reassuring sign of the baby's well-being, but it's not uncommon for some women to remain unaware of their pregnancy until this point if they have no other symptoms.

Throughout pregnancy, healthcare providers monitor the baby's development, including their position in the uterus. While a breech position, with the baby's head up, can persist late into pregnancy, most babies will turn to a head-down (cephalic) position well before labor, often by 28-30 weeks. However, the baby's position alone does not predict the onset of labor.

IVF Date

If you used in vitro fertilization (IVF) or embryo cryopreservation to get pregnant, you could use the date of your IVF transfer to calculate your due date. For example, if the provider transferred the embryos five days after retrieving your eggs, you can count ahead 261 days from that date.

Furthermore, if your eggs were transferred three days after they were retrieved, you should count 263 days to the due date. Typically, you won't have to make these calculations, though, because the provider will calculate the date and let you know.

Gynecological Examination

When there's a chance you may be pregnant, your doctor will probably conduct a pelvic exam. They will look for various symptoms, telling them you may or may not be pregnant. It's important to mention that the signs doctors generally look for aren't definitive pregnancy signs. However, they are often some of the first symptoms that appear.

A gynecological exam is a great way to determine if you are pregnant around the six-week mark. This is the time when your vaginal lining begins to darken as the veins become more visible. The condition is known as Chadwick's Sign and isn't visible until around week 6.

Signs Labor is Imminent

Toward the end of pregnancy, feelings tend to become overwhelming as you grow anxious to meet your new pride and joy. And given that you've been pregnant for a long, most women can't wait to get past the last few weeks.

If you are antsy and wondering if you are getting close, watch for these early signs of labor:

  • Cramps: Some women experience period cramps, which are distinct from Braxton Hicks contractions. They usually come and go over hours or days and are not unbearable, but noticeable.
  • Pelvic Pressure: You may also experience pelvic or vaginal pressure, which is typically due to a process known as "lightening." This occurs when the baby moves down into the pelvis, making you feel as if the baby has "dropped."
  • Mucus Plug: If you notice a drastic change in your vaginal discharge, it may mean you've lost your mucus plug. This plug used to form a seal that protected your baby from bacteria entering from the outside.
  • Changes in your discharge: Your discharge may become thicker, stickier, slightly pink, or even watery.
  • Fatigue: You feel more tired than usual.
  • Diarrhea
  • Sharp, burning pains in your crotch
  • A burst of energy: This is often associated with nesting, when a mother is preparing her home environment for the birth of her baby.

Though just having one of these symptoms may not signal that labor is near, if you have several of the symptoms, it may mean you'll meet your baby within a few days!