Conception Date Calculator

Find out when your baby was likely conceived based on your due date or last period.

Calculate Based On:

Select Estimated Due Date:

Estimated Conception Date

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Conception typically occurs during your fertile window (approx. 2 weeks after the first day of your last period).

Likely Fertile Window --

First Heartbeat (~Wk 6) --

First Trimester End (~Wk 12) --

Estimated Due Date --

How Is Conception Date Calculated?

Conception usually takes place around 11 to 21 days after the first day of your last menstrual period (LMP) for women with a standard 28-day cycle. If you know your due date, conception is typically 266 days (38 weeks) before your expected delivery date.

Frequently Asked Questions

Conception Date FAQs

How accurate is the estimated conception date calculation? +

Conception typically occurs within 24 hours of ovulation, which is usually 14 days after the first day of your last menstrual period (LMP) for a standard 28-day cycle.

What is the fertile window? +

The fertile window consists of the 5 days leading up to ovulation plus the day of ovulation, as sperm can survive in the female reproductive tract for up to 5 days.