Pregnancy Date Calculator

Use this calculator to determine your due date or the date your baby was conceived.

To determine your due date, enter the date of your last menstrual period. If you already know your due date, you can enter that and "calculate backwards" when conception occurred. The bottom part of the form tells you how many weeks pregnant you are today or on the date of your choice. You can also determine on what date you will be the number of weeks pregnant that you enter.

Keep in mind that this calculator is based on a 28-day menstrual cycle, and might not be accurate for women whose cycle varies from that schedule.

How your due date is calculated: Your due date is estimated by adding 40 weeks (280 days) to the approximate first day of your last menstrual period. Only 5% of women deliver their babies on their projected due date, so this date should be used as an estimate - it is not an exact calculation. (Days of the week are optional. The calculator will automatically determine them.)