👶 Gestational Age Calculator
Find out how many weeks pregnant you are today, based on the first day of your last menstrual period.
What gestational age means
Gestational age is the standard way pregnancy length is measured in weeks, counted from the first day of your last menstrual period (LMP) rather than from the date of conception, which usually happens about two weeks later.
How this calculator works
Enter the first day of your last period and your usual cycle length. The calculator counts the number of days that have passed since then to find your current gestational age in weeks and days, identifies your trimester, and projects an estimated due date 280 days from your last period, adjusted for a cycle length that differs from the average 28 days.
This method is the same one used at most prenatal visits, though an early ultrasound can sometimes give a more precise estimate. This tool is for general educational and planning purposes only and is not a substitute for care from a qualified healthcare provider.