Conception Date Calculator

Estimated conception date and fertile window from the last period or a known due date.

Also known as when did i conceive, conception calculator, date of conception.

Enter values

Result

Estimated conception

Sunday, September 13, 2026

Informational estimate only; conception can occur across a multi-day fertile window.

Estimated conception date and fertile window from the last period or a known due date.

Also known as: when did i conceive, conception calculator, date of conception.

Enter i know the, date, cycle length.
The result updates instantly as you type — press Calculate (or Enter) at any time.
Review the breakdown shown under the main result.
Use Copy result or Share to save the answer or send a link with your inputs.

Conception ≈ ovulation ≈ LMP + (cycle length − 14 days)

Using the values pre-filled in the calculator above:

the calculator returns: