Gestational Age Calculator

Standard pregnancy tracking measures gestational age using a full-term duration of 280 days (or 40 weeks) from the start of the last menstrual period. The mathematical formula relies on subtracting the calculated start date from today's date. Specifically, if you know your Expected Due Date (EDD), the baseline conception or starting point is determined by subtracting 280 days from that date. The formula is: gestational_age = today - (EDD - 280). This yields the exact number of days, which are then easily converted into completed weeks and days.

Imagine you have an Expected Due Date (EDD) set for December 31, 2024, and today's date is September 22, 2024. First, we find the estimated start of the pregnancy by subtracting 280 days from December 31, 2024, which brings us to March 26, 2024. Next, we calculate the difference between today (September 22, 2024) and March 26, 2024. This total is 180 days. Dividing 180 days by 7 gives us 25 weeks and 5 days of gestational age, helping you track your progress precisely into the third trimester.

Keep track of your dates by noting your first ultrasound measurements early in the first trimester, as these provide the most accurate dating baseline. Always use the same reference method consistently throughout your prenatal care visits. Remember that due dates are merely estimates, and only a small percentage of babies arrive precisely on their forecasted due date.