Conception Date Calculator
Conception usually happens around ovulation, not on the day of the last period. Estimate it from your last period or work backward from your due date, and see the likely window rather than a single certain day.
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From the last period
In an average 28-day cycle, ovulation — and so conception — happens about 14 days after the first day of the last period. That is the default estimate. Because sperm survive a few days, the actual conception can fall anywhere in a short window around ovulation, which the calculator shows.
From the due date
A due date is 280 days after the last period, and conception is about 266 days before the due date. So if you know your due date (say from an ultrasound), conception ≈ due date − 266 days. Switch the method above to use this — it can be more accurate than the last-period estimate when the due date came from a scan.
Why it is a window, not a day
Conception cannot be pinned to a single certain date from a calendar alone. Ovulation timing varies between people and cycles, and sperm can fertilize an egg for several days after intercourse. Treat the result as the most likely window; only medical dating (an early ultrasound) narrows it further.
Informational and educational result. Not a substitute for professional advice.
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