How to Use the Pregnancy Due Date Calculator
Enter the requested values, review the units, and select Calculate Pregnancy Due Date. The result updates immediately using the formula below.
Formula
The estimate adds 280 days (40 weeks) to the first day of the last menstrual period. Clinical dating may differ.
Example and Accuracy
The default values provide a working example. Change any input to calculate your own result. The calculator keeps full internal precision and rounds displayed values for readability.
Important Note
This calculator provides an informational estimate. Verify critical financial, medical, construction, scientific, or legal decisions with an appropriate qualified professional.
Calculation Standards
This tool uses documented formulas and high-precision internal values. Displayed results may be rounded for readability. Review the assumptions and verify important decisions with a qualified professional.
Read our calculation methodology