Conception Date Calculator
Estimate the likely conception dates based on your due date.
Due Date
Likely Conception Window
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The Fertile Window
Conception is not a single instant but a process. It requires an egg (which lives for 12-24 hours) to meet sperm (which can live for up to 5 days inside the body).
Timing is Everything
Because sperm can survive for days, your fertile window is actually about 6 days long: the 5 days leading up to ovulation and the day of ovulation itself.
This calculator estimates that massive biological rollback from your due date to find that likely window. Keep in mind that cycle irregularities can shift this window by several days.