Pregnancy Due Date Calculator
Calculate your estimated due date and track your pregnancy progress. Find out how many weeks and days pregnant you are, your current trimester, and important pregnancy milestones.
Enter the first day of your last menstrual period. The due date is calculated as 40 weeks (280 days) from this date.
Enter your information above to calculate your due date
Table of Contents
What is a Pregnancy Due Date Calculator?
A pregnancy due date calculator is a tool that estimates your baby's due date and tracks your pregnancy progress. It calculates how far along you are in your pregnancy, determines which trimester you're in, and shows important pregnancy milestones.
The calculator uses standard medical formulas based on your last menstrual period (LMP), conception date, or ultrasound measurements to provide an estimated due date (EDD). While the actual due date can vary, most babies are born within two weeks before or after the estimated due date.
Our calculator provides comprehensive information including your current gestational age in weeks and days, trimester progress, and key pregnancy milestones to help you track your pregnancy journey.
How it Works
Our pregnancy due date calculator uses established medical formulas to calculate your estimated due date. Here's how it works:
- Choose Calculation Method: Select from LMP (Last Menstrual Period), Conception Date, or Ultrasound measurements
- Enter Your Information: Input the relevant date(s) based on your chosen method
- Automatic Calculation: The calculator automatically computes your estimated due date and current gestational age
- Track Progress: View your current trimester, progress percentage, and important pregnancy milestones
The calculator handles all date calculations automatically, accounting for varying month lengths and providing accurate results based on standard pregnancy dating methods.
Calculation Methods
Last Menstrual Period (LMP) Method
This is the most common method used by healthcare providers. The estimated due date is calculated as 40 weeks (280 days) from the first day of your last menstrual period. This method assumes a 28-day menstrual cycle with ovulation occurring on day 14.
Formula: EDD = LMP + 280 days
Conception Date Method
If you know the exact date of conception, you can use this method. The estimated due date is calculated as 38 weeks (266 days) from the conception date.
Formula: EDD = Conception Date + 266 days
Ultrasound Method
Early ultrasounds (typically performed in the first trimester) can provide very accurate gestational age measurements. Enter the date of your ultrasound and the gestational age provided by your healthcare provider, and the calculator will determine your due date.
This method is often the most accurate, especially when performed early in pregnancy, as it directly measures fetal development.
Pregnancy Trimesters
First Trimester (Weeks 0-12)
The first trimester is a critical period of development. During this time, the baby's major organs and body systems begin to form. This is when most women discover they're pregnant and may experience early pregnancy symptoms like morning sickness and fatigue.
Key Developments: Neural tube formation, heart begins beating, limbs start to form, and all major organs begin developing.
Second Trimester (Weeks 13-26)
Often called the "honeymoon period" of pregnancy, the second trimester is when many women feel their best. Morning sickness typically subsides, and the baby's movements become noticeable. The baby grows rapidly during this period.
Key Developments: Baby can hear sounds, movements become stronger, sex can be determined via ultrasound, and the baby begins to develop sleep-wake cycles.
Third Trimester (Weeks 27-40)
The final trimester is when the baby gains most of its weight and prepares for birth. The mother may experience more discomfort as the baby grows larger, and preparations for delivery begin.
Key Developments: Rapid weight gain, lungs mature, baby moves into birth position, and final preparations for delivery occur.
Pregnancy Milestones
First Trimester Ends (12 weeks, 6 days)
The end of the first trimester marks a significant milestone. The risk of miscarriage decreases significantly, and many women choose to share their pregnancy news around this time.
Second Trimester Ends (26 weeks, 6 days)
By the end of the second trimester, the baby is viable outside the womb (with medical intervention). The baby's movements are strong and regular.
Full Term (37 weeks)
At 37 weeks, a baby is considered full-term and can be born at any time. Babies born at 37 weeks or later typically have fully developed lungs and are ready for life outside the womb.
Estimated Due Date (40 weeks)
The estimated due date is calculated as 40 weeks from the last menstrual period. Only about 5% of babies are born exactly on their due date, but most are born within two weeks before or after.
Post-Term (42 weeks)
Pregnancies that extend beyond 42 weeks are considered post-term. Healthcare providers may recommend induction of labor if the pregnancy continues past this point.
Frequently Asked Questions
The estimated due date is just that—an estimate. Only about 5% of babies are born exactly on their due date. Most babies are born within two weeks before or after the estimated due date. Early ultrasounds (before 14 weeks) tend to provide the most accurate due dates.
Early ultrasounds (performed in the first trimester) are generally considered the most accurate method for determining due dates, as they directly measure fetal development. However, the LMP method is the standard used by most healthcare providers and is very reliable when the date is known accurately.
The LMP method assumes a 28-day cycle with ovulation on day 14. If your cycle is longer or shorter, or if you ovulate on a different day, the due date may need adjustment. An early ultrasound can provide a more accurate due date if your cycle length varies significantly.
Yes, your healthcare provider may adjust your due date based on ultrasound measurements, especially if there's a significant difference from the LMP-based calculation. Early ultrasounds (before 14 weeks) are most reliable for dating adjustments.
Full term refers to a pregnancy that has reached 37 weeks. Babies born at 37 weeks or later are considered full-term and typically have fully developed lungs and are ready for life outside the womb. Babies born before 37 weeks are considered preterm.
It's normal for pregnancies to extend beyond the due date. Most healthcare providers will monitor you closely after 40 weeks. If you reach 42 weeks (post-term), your provider may recommend induction of labor, as the risks to both mother and baby can increase after this point.
No. This calculator is for informational purposes only and should not replace professional medical advice, diagnosis, or treatment. Always consult with your healthcare provider for accurate pregnancy dating, monitoring, and care throughout your pregnancy.