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Date & Time
Conception Date Calculator
Pregnancy is counted from the first day of the last menstrual period, which is about two weeks before conception actually occurs. That offset is why the estimated due date and the estimated conception date differ by roughly fourteen days.
How it works
Estimated due date
Average cycle length
Estimated conception date
First day of last period
Estimated implantation
Days since last period
Frequently asked questions
How do I use the Conception Date Calculator?
Fill in the fields above โ the result recalculates instantly as you type. Everything runs in your browser, so the values you enter are never collected or stored.
Is this calculator free?
Yes. It is completely free, requires no account, and works on phones, tablets and desktops.