Pregnancy Calculator
Calculator Description
The Pregnancy Calculator can estimate a pregnancy schedule based on the provided due date, last period date, ultrasound date, conception date, or IVF transfer date.
Modify the values and click the calculate button to use
Calculate Based On:
Your Pregnancy Timeline
Important Milestones
Pregnancy Term & Due Date
Pregnancy is a term used to describe a woman's state over a time period (~9 months) during which one or more offspring develops inside of a woman. Childbirth usually occurs approximately 38 weeks after conception, or about 40 weeks after the last menstrual period. The World Health Organization defines a normal pregnancy term to last between 37 and 42 weeks.
During a person's first OB-GYN visit, the doctor will usually provide an estimated date (based on a sonogram) at which the child will be born, or due date. Alternatively, the due date can also be estimated based on a person's last menstrual period.
While the due date can be estimated, the actual length of pregnancy depends on various factors, including age, length of previous pregnancies, and weight of the mother at birth. However, there are still more factors affecting natural variation in pregnancy terms that are not well understood.
Studies have shown that fewer than 4% of births occur on the exact due date, 60% occur within a week of the due date, and almost 90% occur within two weeks of the due date. As such, while it is possible to be fairly confident that a person's child will be born within about two weeks of the due date, it is currently not possible to predict the exact day of birth with certainty.