Discover your baby's estimated due date with our simple calculator. Enter the first day of your last menstrual period (LMP) to get an important date for your pregnancy journey.
Your Estimated Due Date (EDD), often just called a due date, is the predicted day your baby will be born. The most common and reliable way to calculate this is by using the first day of your last menstrual period (LMP). A full-term pregnancy is considered to be **280 days (or 40 weeks)** from your LMP. This date is essential for you and your healthcare provider to track your pregnancy milestones.
While it's exciting to have a date to look forward to, it's crucial to remember that your EDD is just an approximation. Here are a few key facts to keep in mind:
Think of your EDD as a guide for your final weeks of pregnancy, but know that your baby will ultimately set their own birthday!
Disclaimer: This calculator provides an estimate and is not a substitute for professional medical advice. Always consult with your doctor or midwife for accurate dating and prenatal care.
The calculator above uses Naegele's rule: add 7 days to the first day of your last menstrual period, subtract 3 months, add a year. It assumes a textbook 28-day cycle with ovulation on day 14 — which is why it works best as a starting estimate rather than a promise.
The honest statistics: only about 5% of babies arrive on their due date, and roughly 80% are born within two weeks on either side. ACOG defines full term as 39 weeks 0 days through 40 weeks 6 days; 37w0d–38w6d is "early term," 41w0d–41w6d is "late term," and 42 weeks and beyond is "postterm." Your provider watches which window you land in far more closely than the single date.
When the LMP is unknown or cycles are irregular, a first-trimester ultrasound (crown-rump length measurement) dates the pregnancy more accurately — usually within 5–7 days. If the ultrasound date and the LMP date disagree by more than that, most providers switch to the ultrasound date. For a clear, doctor-reviewed overview of how due dates are set and what can shift them, see MedlinePlus on estimating the delivery date.
Think of your due date as the midpoint of a healthy delivery window, not an appointment. "Overdue" before 42 weeks is common and usually fine; your provider monitors the placenta and fluid and will discuss options only if the pregnancy extends well past term.
Maintained by Live Fitness Check. Last updated: August 9, 2026. How we test our calculators .
Estimates a pregnancy due date from the first day of the last menstrual period.
The calculator applies the conventional 280-day pregnancy-dating interval from the first day of the last menstrual period. The calculation uses the first day of the last menstrual period.
Cycle length, uncertain dates and ultrasound findings can change the best obstetric estimate. Use the number as an estimate and consider professional advice when the result may affect health, treatment, pregnancy, nutrition, exercise safety or another important decision.
