Due Date Calculator
The Due Date Calculator can be used to estimate the due date based on your personal biological cycles.
Though pregnancy begins at conception, it is best to estimate the due date from the first day of a woman's last menstrual period (LMP). Counting from the LMP, pregnancy usually lasts between 37 and 42 weeks, with the due date at 40 weeks, or 38 weeks after conception. Forty weeks is around nine months and six days, or 10 lunar months.
An early sonograph can determine the age of the pregnancy fairly accurately. Doctors typically express the age of a pregnancy (i.e., an "age" for an embryo) in terms of the "menstrual date" based on the first day of a woman's last menstrual period.