Pregnancy Due Date Calculator

Calculate your estimated due date from your last menstrual period

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Estimated Due Date (EDD)
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Weeks pregnant
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Days until due date
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Current trimester
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Est. conception date
Key Pregnancy Milestones
⚠ This calculator provides an estimate only. Only a healthcare provider can confirm your due date. Actual birth may occur 2–3 weeks before or after the EDD.
How to Use the Due Date Calculator
1
Enter the first day of your last menstrual period (LMP)
2
Select your average cycle length (28 days is most common)
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Click Calculate Due Date to see your EDD and milestones
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View your current trimester, weeks pregnant, and key dates
About Due Date Calculation

The estimated due date (EDD) is calculated using Naegele's Rule — add 280 days (40 weeks) to the first day of your last menstrual period. This assumes a 28-day cycle. For cycles longer or shorter than 28 days, the calculator adjusts accordingly.

Pregnancy is divided into three trimesters: First trimester (weeks 1–12), Second trimester (weeks 13–27), and Third trimester (weeks 28–40). Only about 4% of babies are born exactly on their due date — most arrive within 2 weeks before or after.

Frequently Asked Questions
This calculator uses Naegele's Rule, the standard method used by healthcare providers. It's a reliable estimate, but ultrasound measurements in the first trimester are more accurate. Only about 4–5% of babies are born on their exact due date.
If you don't know your LMP or have irregular periods, your doctor will use an early ultrasound (ideally before 14 weeks) to determine your due date based on the baby's measurements. This is often more accurate than LMP-based calculation.
See a doctor as soon as you have a positive pregnancy test. Early prenatal care (ideally in the first trimester) is important for monitoring the pregnancy, confirming the due date, and starting essential prenatal vitamins including folic acid.