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About the Conception Calculator
This calculator estimates the date when conception likely occurred. Enter a due date or a birth date, and it returns an estimated conception date plus the likely range of days around it.
The calculation uses the standard 266-day gestation period counted from conception to the estimated due date. It subtracts 266 days from the date you enter and shows a typical fertile window of several days. Results depend on the accuracy of your due date or birth date. Keep in mind that ovulation timing varies between people, so treat the output as an estimate, and consider confirming dates with a healthcare professional.
- Enter your due date or the baby's date of birth.
- Run the calculation to generate the estimate.
- Read the estimated conception date and the range shown.