Conception Date Calculator
Estimate conception by subtracting 266 days from the due date, or find a due date from known conception. Includes an assumed fertile window; not proof of fertilization date.
01
Choose the known dateThe estimate subtracts 266 days from the due date. The displayed window is an assumed fertile window around ovulation, not proof or a confidence interval for fertilization.
All dates are Gregorian. Calculations run in your browser without sending your data.
———
Pregnancy start0%Due date
An informational estimateClinical dating can differ, especially after an early ultrasound. Follow the date and care plan confirmed by your healthcare professional.