Gestational Age Calculator
Calculate the gestational age of a pregnancy.
Enter a date to see your results.
From the moment you confirm a pregnancy, one of the first and most fundamental pieces of information you'll track is the gestational age. It's the standard used by healthcare providers worldwide to date a pregnancy, monitor fetal development, and estimate a due date. This gestational age calculator is a simple tool designed to help you quickly determine your pregnancy's progress based on the date of your last menstrual period (LMP).
What is Gestational Age?
Gestational age is the term used to describe how far along a pregnancy is. It's measured in weeks and days, starting from the **first day of your last menstrual period (LMP)**.
This often causes a bit of confusion. Since conception usually happens about two weeks after your period starts (around the time of ovulation), counting from the LMP means that for the first two weeks of your "gestational age," you weren't actually pregnant yet. This is simply a convention that provides a standardized and reliable starting point for doctors to date a pregnancy, as most women know when their last period started, but few know the exact date of conception.
Gestational Age vs. Fetal Age
It's helpful to understand the difference between two related terms:
- Gestational Age: Measured from the first day of your LMP. This is the standard used in all clinical settings. A full-term pregnancy is considered to be 40 weeks of gestational age.
- Fetal Age (or Conceptional Age): This is the actual age of the growing fetus, measured from the date of conception. The fetal age is always about two weeks less than the gestational age.
When your doctor tells you that you are "10 weeks pregnant," they are referring to the gestational age.
How to Use the Calculator
This calculator makes it easy to find your current gestational age:
- Enter Your Last Period Date: Use the calendar to select the first day of your last normal menstrual period.
The calculator will automatically compare that date to today's date and calculate the total number of days that have passed. It then converts this into the standard format of weeks and days. It will also provide an estimated due date (EDD) by adding 280 days (40 weeks) to your LMP.
Why is Gestational Age So Important in Prenatal Care?
Accurately determining gestational age is critical for providing appropriate prenatal care. It influences the entire schedule of your pregnancy journey.
- Timing of Tests and Screenings: Many prenatal tests are time-sensitive. For example, the nuchal translucency scan is performed between 11 and 14 weeks, and tests for gestational diabetes are typically done around 24-28 weeks. An accurate gestational age ensures these tests are performed at the correct time for reliable results.
- Monitoring Fetal Growth: Your provider will track your baby's growth against standard milestones for their gestational age. If a baby is measuring significantly smaller or larger than expected for their age, it could indicate a potential issue that needs closer monitoring.
- Managing Pregnancy Complications: If complications arise, knowing the precise gestational age is vital for making decisions about management, such as the timing of delivery.
- Determining Fetal Viability and Maturity: In cases of preterm labor, gestational age is a key factor in assessing the baby's chances of survival and the level of medical intervention needed.
The Role of Ultrasound in Confirming Gestational Age
While calculating from the LMP is the standard initial method, it assumes a regular 28-day cycle with ovulation on day 14. For women with irregular cycles, this method can be inaccurate.
For this reason, a first-trimester ultrasound is considered the gold standard for dating a pregnancy. By measuring the baby's crown-rump length (CRL), a sonographer can determine the gestational age with a high degree of accuracy. If the ultrasound dating differs from the LMP dating by more than about a week, your healthcare provider will likely adjust your due date based on the ultrasound measurement.
Use this calculator as a convenient way to track your progress and understand your pregnancy timeline, but always rely on the gestational age and due date confirmed by your healthcare provider for all medical purposes.
Disclaimer: This calculator provides an estimate based on the Last Menstrual Period. It is for informational purposes only and is not a substitute for professional medical advice. Always consult with your doctor or midwife for the official dating of your pregnancy.
Enter values to see the results.
From the moment you confirm a pregnancy, one of the first and most fundamental pieces of information you'll track is the gestational age. It's the standard used by healthcare providers worldwide to date a pregnancy, monitor fetal development, and estimate a due date. This gestational age calculator is a simple tool designed to help you quickly determine your pregnancy's progress based on the date of your last menstrual period (LMP).
What is Gestational Age?
Gestational age is the term used to describe how far along a pregnancy is. It's measured in weeks and days, starting from the **first day of your last menstrual period (LMP)**.
This often causes a bit of confusion. Since conception usually happens about two weeks after your period starts (around the time of ovulation), counting from the LMP means that for the first two weeks of your "gestational age," you weren't actually pregnant yet. This is simply a convention that provides a standardized and reliable starting point for doctors to date a pregnancy, as most women know when their last period started, but few know the exact date of conception.
Gestational Age vs. Fetal Age
It's helpful to understand the difference between two related terms:
- Gestational Age: Measured from the first day of your LMP. This is the standard used in all clinical settings. A full-term pregnancy is considered to be 40 weeks of gestational age.
- Fetal Age (or Conceptional Age): This is the actual age of the growing fetus, measured from the date of conception. The fetal age is always about two weeks less than the gestational age.
When your doctor tells you that you are "10 weeks pregnant," they are referring to the gestational age.
How to Use the Calculator
This calculator makes it easy to find your current gestational age:
- Enter Your Last Period Date: Use the calendar to select the first day of your last normal menstrual period.
The calculator will automatically compare that date to today's date and calculate the total number of days that have passed. It then converts this into the standard format of weeks and days. It will also provide an estimated due date (EDD) by adding 280 days (40 weeks) to your LMP.
Why is Gestational Age So Important in Prenatal Care?
Accurately determining gestational age is critical for providing appropriate prenatal care. It influences the entire schedule of your pregnancy journey.
- Timing of Tests and Screenings: Many prenatal tests are time-sensitive. For example, the nuchal translucency scan is performed between 11 and 14 weeks, and tests for gestational diabetes are typically done around 24-28 weeks. An accurate gestational age ensures these tests are performed at the correct time for reliable results.
- Monitoring Fetal Growth: Your provider will track your baby's growth against standard milestones for their gestational age. If a baby is measuring significantly smaller or larger than expected for their age, it could indicate a potential issue that needs closer monitoring.
- Managing Pregnancy Complications: If complications arise, knowing the precise gestational age is vital for making decisions about management, such as the timing of delivery.
- Determining Fetal Viability and Maturity: In cases of preterm labor, gestational age is a key factor in assessing the baby's chances of survival and the level of medical intervention needed.
The Role of Ultrasound in Confirming Gestational Age
While calculating from the LMP is the standard initial method, it assumes a regular 28-day cycle with ovulation on day 14. For women with irregular cycles, this method can be inaccurate.
For this reason, a first-trimester ultrasound is considered the gold standard for dating a pregnancy. By measuring the baby's crown-rump length (CRL), a sonographer can determine the gestational age with a high degree of accuracy. If the ultrasound dating differs from the LMP dating by more than about a week, your healthcare provider will likely adjust your due date based on the ultrasound measurement.
Use this calculator as a convenient way to track your progress and understand your pregnancy timeline, but always rely on the gestational age and due date confirmed by your healthcare provider for all medical purposes.
Disclaimer: This calculator provides an estimate based on the Last Menstrual Period. It is for informational purposes only and is not a substitute for professional medical advice. Always consult with your doctor or midwife for the official dating of your pregnancy.