Conception Date Calculator
From Last Menstrual Period
Calculate conception date from LMP
From Due Date
Work backwards from your due date
Formula
From LMP: Conception ≈ LMP + 14 days | From Due Date: Conception ≈ Due Date - 266 days | Due Date = LMP + 280 days
Frequently Asked Questions
When does conception occur?
Conception typically occurs during ovulation, around day 14 of a 28-day menstrual cycle. Sperm can survive up to 5 days, so intercourse a few days before ovulation can still result in conception.
How accurate is this conception date?
This calculator estimates conception based on a standard 28-day cycle with ovulation on day 14. If your cycle is longer or shorter, the actual conception date may differ by several days.
What is the fertile window?
The fertile window is the approximately 6-day period when pregnancy is possible: the 5 days before ovulation and the day of ovulation itself. Sperm can survive in the body for up to 5 days, while the egg is viable for about 12-24 hours.
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