Pregnancy Conception Calculator
The Pregnancy Conception Calculator estimates the date of conception based on the expected due date of the pregnancy, last period date, or ultrasound date.
Calculate Conception Date
Select a method to calculate your conception date:
Calculation Results
When Did I Conceive?
When exactly did I get pregnant? Many women ask this question when trying to figure out the exact day their pregnancy began. Often, gestational age, or the age of the baby, is calculated from the first day of the mother's last menstrual period. Biologically, the baby was not conceived until ovulation and the fertilization of the egg, which usually happens at least 10 days after the first day of the mother's last menstrual period.
Because there are many factors surrounding conception, it is difficult to pinpoint an exact date of conception. This calculator helps to estimate the date range of real conception and a possible range of days during which sexual intercourse might have led to conception. There are a few methods that can be used to estimate the conception dates.
Last Menstrual Period
Conception usually occurs around 11-21 days after the first day of the last period of a woman who has a regular period. The estimation of conception date is based on this, but is rarely ever exact since it is difficult to know exactly when ovulation occurs.
Due Date
An estimated due date, usually based on a sonogram, is typically obtained from a healthcare provider during a prenatal visit. Based on this due date, a range of possible conception dates can be calculated.
Ultrasound
An ultrasound, on a basic level, uses sound waves to create images of internal body structures. An ultrasound used in the context of examining the progress of the fetus in pregnant women is referred to as an "obstetric ultrasound."
Conception Timing Based on Method
| Calculation Method | Typical Conception Timing | Accuracy |
|---|---|---|
| Last Menstrual Period | 11-21 days after LMP | Moderate (depends on cycle regularity) |
| Due Date | About 266 days before due date | Good (if due date is accurate) |
| Ultrasound | Based on fetal measurements | High in early pregnancy |
Pregnancy Timeline
[Pregnancy Timeline Visualization]
Fertilization, Conception, and Pregnancy
Fertilization and conception are terms that are often used interchangeably. This calculator uses the medical and scientific definition of the terms. Fertilization occurs when the sperm and the egg combine in the fallopian tube, producing a fertilized egg, and beginning the process in which an embryo develops.
Conception refers to the process of becoming pregnant, which scientifically involves both fertilization as well as implantation into the wall of the uterus.
Key Differences
| Term | Definition | Timing |
|---|---|---|
| Fertilization | Sperm and egg combine | Usually around ovulation |
| Implantation | Fertilized egg attaches to uterus | 6-12 days after fertilization |
| Conception | Complete process (fertilization + implantation) | Varies (up to 12 days after fertilization) |