Conception Calculator

Given baby's arrival date, work out the days intercourse could plausibly have conceived.

Due date OR birth date

Enter the required values above to see your result.

How the Conception Calculator works

The calculation follows the standard method used across the US — no shortcuts, no hidden assumptions. Here is exactly what happens behind the scenes:

How does the Conception Calculator work?

Enter your numbers above and results update instantly using standard formulas, computed entirely on your device.

Is the Conception Calculator free to use?

Yes — completely free with no signup required, and it works on phones, tablets, and desktops.

Estimate when conception occurred from the due date or last menstrual period, including IVF transfer dates.

Fitness & Health

Predict ovulation dates and fertile windows from cycle start and length over coming months.

Fitness & Health

Predict your due date from the first day of your last period (adjusted for cycle length) or from conception.

Fitness & Health