Pregnancy calculator is a tool that helps you determine the approximate due date by inputting simple information about your monthly cycle. Please note that this is just a general tool and the theoretical date is only an estimate based on ideal conditions. Every individual pregnancy is unique and subject to variable conditions that may add to or shorten the actual delivery date.
The calculation is done using: Naegele's Rule for Pregnancy. Naegele's Rule (sometimes spelled as Nagel's Rule) predicts an estimated due date based on the onset of the woman's last menstrual period. You simply add on nine months and seven days to arrive at the due date. Some studies indicate slightly longer, particularly for first-time mothers.