Conception Date Calculator

Some people search “who got me pregnant calculator by date of birth” when they really want to know when conception most likely happened. A conception date calculator estimates that window from a few known dates.

How conception timing is estimated

Pregnancy is usually dated from the first day of your last menstrual period (LMP). Conception typically occurs around ovulation — roughly two weeks after the LMP in an average 28-day cycle. If you know your due date instead, conception is estimated as about 266 days (38 weeks) before it.

The fertile window

Because sperm can survive several days and the egg is viable for about a day, conception could result from intimacy across a window of roughly five to six days, not a single moment. That’s why a calculator gives a likely range rather than one exact date.

Why it can’t give a definitive answer

Cycles vary, ovulation shifts, and early ultrasounds sometimes adjust dating by a week or more. So while a conception estimate is useful for understanding timing, it cannot by itself confirm paternity or pinpoint a single day.

When you need certainty

For medical accuracy, an early dating ultrasound is the best guide, and for questions of paternity, a DNA test is the only reliable answer. Your doctor or midwife can advise on both.

Estimate your due date

Use the Pregnancy Due Date tool to estimate your due date and conception window.