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About this tool
Estimate dates using standard pregnancy dating inputs.
This is an estimated due date based on menstrual history, not a clinical determination. Ultrasound dating and clinician assessment may change it.
How pregnancy due dates are estimated
The calculator adds approximately 280 days to the first day of the last menstrual period and adjusts for the stated cycle length.
Worked example
For a 28-day cycle, the estimate is 40 weeks from the first day of the last period.
Frequently asked question
Is the calculated due date exact?
No. It is an estimate; ultrasound dating and clinical assessment may revise it.