Pregnancy Conception Calculator

Enter your due date to estimate when conception likely happened and the fertile window around it.

How this calculator works

Conception is usually estimated 266 days before the due date. The fertile window covers about five days before ovulation through the day after, because sperm can survive for several days.

Frequently asked questions

Can I find out the exact conception date?

Not usually. Ovulation timing and sperm survival make it an estimate within a few days.

Estimates only. Conception can happen several days either side of the estimated date.