Gestational Age Calculator

Calculate due date, track pregnancy progress, and get personalized fetal development information. Trusted by expectant parents worldwide.

Last Menstrual Period (LMP)
Conception Date
Ultrasound Dating
IVF/ET Date
This is the most common method for calculating due date
Most women have cycles between 21-35 days
If you want to calculate for a specific date other than today
Your Pregnancy Calculation Results
Week 12
12
Gestational Age
12 weeks, 0 days
08/19/2026
Estimated Due Date
40 weeks from LMP
1st
Current Trimester
Weeks 1-13
30%
Pregnancy Progress
28 weeks remaining
08/05/2026
Earliest Expected
08/19/2026
Most Likely Due Date
09/02/2026
Latest Expected
Week 12
Trimester 1
Trimester 2
Trimester 3
First Trimester
Weeks 1-13
Completed
Second Trimester
Weeks 14-27
Upcoming
Third Trimester
Weeks 28-40
Upcoming

Fetal Development at Week 12

Week 12
Baby's Size & Development
Approximate size: 2.1 inches | Weight: 0.49 ounces
Reflexes develop
Fetal development progresses
Fingers and toes fully separated
Baby continues to grow and develop
Can make a fist, kidneys begin producing urine
Organs continue to mature
Lime
About 2.1 inches long
Maternal Changes & Symptoms
What to expect during this week
Nausea may start to improve
Typical pregnancy symptoms for this stage
Energy levels may increase
Your body continues to adapt to pregnancy
Visible baby bump possible, less frequent urination
Follow healthcare provider's advice
This Week's Checklist
Recommended actions for this stage
First trimester screening (if desired)
Recommended for week 12
Announce pregnancy to family/friends
Recommended for week 12
Plan maternity leave, consider prenatal classes
Recommended for week 12

Understanding Gestational Age

Gestational age is a measure of the age of a pregnancy taken from the beginning of the woman's last menstrual period (LMP). It is typically expressed in weeks and days. A full-term pregnancy ranges from 37 weeks to 42 weeks.

Key Pregnancy Milestones
Gestational Age Milestone Typical Events
4 weeks Positive pregnancy test Missed period, early pregnancy symptoms
8-12 weeks First prenatal visit Confirmation of pregnancy, initial tests
12-13 weeks First trimester screening Nuchal translucency ultrasound, blood tests
18-22 weeks Anatomy scan Detailed ultrasound, gender may be determined
24-28 weeks Glucose screening Test for gestational diabetes
37 weeks Full term Baby is considered full term, can arrive any time
40 weeks Estimated due date Average length of pregnancy from LMP

Calculation Methods Explained

LMP Method

The most common method. Due date is calculated as LMP + 280 days (40 weeks). This assumes a 28-day cycle with ovulation on day 14.

Conception Date

If you know the exact conception date, due date is calculated as conception date + 266 days (38 weeks).

Ultrasound Dating

Early ultrasound measurements (especially CRL) provide the most accurate dating. Later ultrasounds are less accurate for dating.

IVF/ET Dating

For IVF pregnancies, due date is calculated from embryo transfer date plus 266 days minus embryo age at transfer.

Frequently Asked Questions

Only about 5% of babies are born on their exact due date. Most are born within two weeks before or after. The due date is an estimate, not a guarantee. Ultrasound dating in the first trimester is more accurate than LMP dating.

If your cycle is longer than 28 days, you likely ovulate later, so your due date may be later than calculated. If your cycle is shorter, you likely ovulate earlier, so your due date may be earlier. You can adjust for this by changing the cycle length in the calculator.

Ultrasound dating uses measurements of the fetus to estimate gestational age. The crown-rump length (CRL) measured between 6-13 weeks is the most accurate. Later measurements (biparietal diameter, head circumference, femur length) are less accurate for dating but good for tracking growth.

Gestational age is measured from the first day of the last menstrual period (LMP). Fetal age (or conceptual age) is the actual age of the fetus from conception. Fetal age is approximately two weeks less than gestational age. Medical professionals use gestational age.

Yes, it's completely normal. About 20-30% of women have minimal or no symptoms in early pregnancy. Lack of symptoms does not necessarily indicate a problem with the pregnancy. However, if you have severe symptoms that suddenly disappear, consult your healthcare provider.