Pregnancy Due Date Calculator
Estimate the expected due date and current gestational age using the method that fits your information.
Based on Naegele's rule
The most common estimate adds 280 days (40 weeks) to the first day of the last menstrual period, assuming a typical 28-day cycle. The conception and ultrasound methods adjust this estimate using more precise information when available.
An estimate, not a diagnosis
Only about 5% of babies are born exactly on the estimated due date. This tool is for general reference only — follow your prenatal care provider's guidance.
Calculated locally, on your device
No personal or health information is sent to any server; the calculation runs entirely in your browser.
Frequently asked questions
Which method is the most accurate?
An early ultrasound (first trimester) is generally considered the most reliable method for dating a pregnancy.
What if my cycle is not 28 days?
This calculator assumes a standard 28-day cycle; irregular cycles may shift the actual due date by several days.
Does the trimester split follow a fixed rule?
This tool uses the common convention of weeks 1–12 for the first trimester, 13–26 for the second, and 27 onward for the third.
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