Pregnancy Due Date Calculator
Calculate your estimated due date (EDD) by entering the first day of your last menstrual period (LMP). Based on Naegele's rule (LMP + 280 days). Also shows your current pregnancy week and trimester. Free and private.
Key Capabilities
How is the due date calculated?
The tool uses Naegele's Rule — the most widely used method in clinical practice. It adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a standard 28-day cycle with ovulation on day 14.
How accurate is the LMP due date?
About 80% of pregnancies deliver within 2 weeks of the calculated EDD. Accuracy depends on cycle regularity. An ultrasound dating scan in the first trimester (7–12 weeks) provides the most accurate EDD and should be used when available.
What are the trimester boundaries?
First Trimester: weeks 1–13. Second Trimester: weeks 14–26. Third Trimester: weeks 27–40+. Most healthcare providers adjust these definitions slightly based on clinical context.
How to Use
Upload your medical document
Open the Pregnancy Due Date Calculator tool and upload your medical document (prescription, lab report, or medical record). Your data stays in your browser — zero server uploads.
AI analysis begins
The tool analyzes your document using specialized medical OCR models trained on healthcare documents. This typically takes 3-8 seconds.
Review extracted information
Review the structured medical information extracted from your document. Copy results or download for your records.
Frequently Asked Questions
How is the due date calculated?
The tool uses Naegele's Rule — the most widely used method in clinical practice. It adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a standard 28-day cycle with ovulation on day 14.
How accurate is the LMP due date?
About 80% of pregnancies deliver within 2 weeks of the calculated EDD. Accuracy depends on cycle regularity. An ultrasound dating scan in the first trimester (7–12 weeks) provides the most accurate EDD and should be used when available.
What are the trimester boundaries?
First Trimester: weeks 1–13. Second Trimester: weeks 14–26. Third Trimester: weeks 27–40+. Most healthcare providers adjust these definitions slightly based on clinical context.
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