Conception Date Calculator
Find out roughly when you conceived, from the first day of your last period or from your due date.
Keep your dates in Prego: a daily countdown, your baby's size each week and a checklist for every trimester.
How conception is estimated
Most people ovulate about 14 days before their next period. In a 28-day cycle that is day 14, so conception usually happens about two weeks after the first day of your last period. From a due date, conception is about 266 days (38 weeks) earlier.
The exact day can't be known: sperm can live for up to 5 days and an egg for about a day, so sex in the five days before ovulation can lead to pregnancy.
Frequently asked questions
Can I find out exactly when I conceived?
Not exactly. You can estimate a likely window of a few days. An early ultrasound gives the most accurate dating of a pregnancy, but even that can only estimate conception.
How many days after sex does conception happen?
Fertilization can happen anywhere from a few minutes to about 5 days after sex, depending on when you ovulate, because sperm can survive in the body for several days.
Is conception the same as implantation?
No. Conception (fertilization) is when sperm meets egg. Implantation, when the embryo attaches to your uterus, happens about 6 to 12 days later.
Estimates only. Your doctor or midwife may give you different dates or targets.