🌱 Conception Calculator
Estimate the likely date your baby was conceived, based on your due date or last menstrual period.
Your Details
Your Result
Conception date is an estimate. The exact day can vary by several days from ovulation timing and sperm survival, which can live in the body for up to 5 days.
How the Conception Calculator Works
Conception typically happens around ovulation, roughly 14 days after the start of the last menstrual period in an average 28-day cycle, or 266 days before the estimated due date.
Formula
From last period: Conception ≈ LMP + 14 days
Likely window: Estimated date − 2 days to Estimated date + 3 days
Why a Range Is Given
Sperm can survive in the reproductive tract for up to five days, and the egg is viable for about 12–24 hours after ovulation, so conception could have occurred anywhere within a several-day window around the estimated date.
Frequently Asked Questions
How accurate is a conception calculator?
It provides a reasonable estimate but not an exact date. Actual ovulation timing varies by individual and cycle.
Is conception the same as ovulation?
Conception occurs when sperm fertilizes the egg, which happens around the time of ovulation, typically within 24 hours of the egg being released.
Can I find my exact conception date?
Only fertility tracking methods like ovulation testing, or a known single act of intercourse, can narrow the conception date more precisely. Otherwise it remains an estimate.