Calculate Your Estimated Due Date
Finding out you are pregnant immediately leads to one question: When is the baby arriving? Our Pregnancy Due Date Calculator uses standard obstetric algorithms to estimate your delivery date, current trimester, and fetal developmental milestones.
How Doctors Calculate Due Dates
You might think a pregnancy is calculated from the exact day of conception, but the medical community uses a different, standardized method:
- The LMP Method (Naegele's Rule): Because the exact day of ovulation and conception is hard to pinpoint, doctors calculate pregnancy from the First Day of your Last Menstrual Period (LMP).
- The 40-Week Timeline: The calculator adds 280 days (40 weeks) to your LMP date. This means that during "Week 1" and "Week 2" of a medical pregnancy timeline, you are not actually pregnant yet—your body is just preparing for ovulation.
- Conception Date Method: If you underwent IVF or were tracking ovulation meticulously (via basal body temperature or LH strips), you can calculate by adding 266 days (38 weeks) directly to the conception date.
How to Use This Tool
- Upload or Input Data: Select your file or paste your data directly into the tool interface. Everything remains on your device.
- Configure & Process: Adjust any optional settings if necessary. The tool will process your data instantly inside your browser.
- Download Result: Preview the output and click the download or copy button to save your final results.
Frequently Asked Questions
How accurate is the estimated due date (EDD)?
It is just an estimate! Only about 4% to 5% of babies are actually born on their exact due date. Most normal pregnancies deliver anywhere between week 37 and week 41.
What if my cycles are longer than 28 days?
Naegele's Rule assumes a perfect 28-day cycle with ovulation on day 14. If you have a longer cycle (e.g., 35 days), you likely ovulated later, meaning your true due date will be pushed back by a week. An early ultrasound is the most accurate way to date a pregnancy.
When does the second trimester start?
The first trimester ends at 13 weeks and 6 days. The second trimester begins on the first day of week 14. The third trimester begins at week 28.