How Your Due Date Is Calculated

Your estimated due date (EDD) is the projected date your baby will be born. This calculator uses **Naegele's rule**, the method most healthcare professionals use to determine a due date. This rule works on the premise that a human pregnancy lasts approximately 280 days, or 40 weeks, from the first day of your Last Menstrual Period (LMP).

Calculation Methods Explained

• Last Menstrual Period (LMP): This is the most common starting point. Your pregnancy timeline actually begins before conception, on the first day of your last period. The calculator adds 280 days to this date to find your EDD. Because not everyone has a 28-day cycle, our calculator adjusts for your unique cycle length for better accuracy.
• Conception Date: If you know when you conceived (through ovulation tracking or assisted reproductive technology), a pregnancy typically lasts 266 days (38 weeks) from this date. If you're unsure about this date, you can use our Pregnancy Conception Calculator to estimate it.

How Accurate Is My Due Date?

It's important to remember that a due date is just an estimate. Only about 5% of babies are born on their exact due date. Most are born within a week or two on either side of this date. Your doctor will likely perform an ultrasound in your first trimester, which is the most accurate way to date a pregnancy and may be used to adjust your due date.

Your Pregnancy Trimesters

Your 40-week pregnancy is divided into three key stages called trimesters. Our calculator shows you when you'll pass from one to the next.

• First Trimester (Week 1 - 13): A time of incredible, rapid development for the baby.
• Second Trimester (Week 14 - 27): Often a period of renewed energy for the mother as the baby continues to grow.
• Third Trimester (Week 28 - Birth): The final stretch where the baby grows and positions for birth.

As you progress through your pregnancy, tracking your health is key. You can monitor your progress with tools like our Pregnancy Weight Gain Calculator to ensure you're on a healthy path.

Disclaimer: This calculator is an informational tool and should not replace consultation with a healthcare professional. All dates are estimations. Always confirm your due date and receive prenatal care from a qualified doctor or midwife.