Your Estimated Due Date (EDD) is the projected delivery date of your baby, calculated as 280 days (40 weeks) from the first day of your Last Menstrual Period (LMP). This calculator uses Naegele's Rule to estimate your delivery date, current gestational age, and likely conception date.
Instantly see exactly how many weeks and days pregnant you are today.
Calculates your EDD accurately even if your menstrual cycle is longer or shorter than 28 days.
Pregnancy dating is not an exact science, but a highly structured clinical estimate. Understanding how your Estimated Due Date (EDD) is determined—and why it might change after an ultrasound—helps you track your pregnancy milestones with confidence.
This calculator uses Naegele's Rule, the historical standard for estimating gestational age. It assumes a perfect 28-day cycle with ovulation on Day 14. Because pregnancy is counted from your period, you aren't technically "pregnant" during the first two weeks.
If your cycles are longer than 28 days, your ovulation date—and thus your conception date—shifts forward. Our EDD Calculator adjusts for this, but an ultrasound will confirm.
An early ultrasound due date is the clinical gold standard. Between 8 and 13 weeks, the sonographer measures the Crown-Rump Length (CRL) of the fetus. Because babies grow at a highly predictable rate early on, this measurement is more accurate than a calendar.
If your ultrasound due date differs from your LMP due date by more than 5-7 days in the first trimester, your doctor will officially change your EDD to the ultrasound date.
A full-term pregnancy is 40 weeks, but this is an average, not a deadline. Delivery date can safely occur anywhere between 37 weeks (early term) and 42 weeks (late term). Spontaneous labor is triggered by the baby, not the calendar.
Do not stress if you pass your due date. Most doctors will not induce labor until you reach 41 weeks, provided the baby's heartbeat and amniotic fluid levels are healthy.
Your due date is more than just a finish line; it dictates the timeline of your prenatal care. Knowing your gestational age ensures you get the right tests at the right time. Here is what to expect as you progress through your pregnancy week by week.
This is the most critical phase for fetal development, as all major organs begin to form. You may experience fatigue, nausea (morning sickness), and breast tenderness. The risk of miscarriage drops significantly after week 12.
Often called the "honeymoon phase" of pregnancy, nausea usually fades and energy returns. This is the time you will likely feel the baby's first movements (quickening) and your belly will visibly pop.
The baby rapidly gains weight and matures its lungs. You may feel increased pelvic pressure, back pain, and Braxton Hicks (practice) contractions. This phase is about finalizing your birth plan and watching for labor signs.
While pregnancy is a natural process, certain symptoms require immediate medical evaluation. Go to the emergency room or call your OB-GYN immediately if you experience heavy vaginal bleeding, severe or persistent abdominal pain, sudden swelling in your face or hands (signs of preeclampsia), a sudden gush of fluid from the vagina, or if your baby stops moving entirely.
Find clear, scientifically-backed answers to the most common questions about calculating your due date, gestational age, and what to expect as your pregnancy progresses.
Community Medicine Specialist