Gestational Age Calculator
Enter the first day of your last period to see exactly how many weeks and days pregnant you are today.
About this calculator
This gestational age calculator counts the exact number of days from the first day of the last menstrual period to today, then converts that into the weeks-and-days format used throughout prenatal care.
It also projects the estimated due date using the standard 40-week (280-day) pregnancy length.
How it works
Enter the first day of your last period
This is the standard starting point used by care providers.
Calculate
The calculator counts the exact days elapsed and converts to weeks and days.
Review the result
See current gestational age and the estimated due date.
Frequently asked questions
Why does gestational age start before conception?
By medical convention, pregnancy is dated from the first day of the last period, which is roughly two weeks before conception actually occurs.
Will my provider's dating match this exactly?
It should closely match if your cycles are regular; providers often adjust based on an early ultrasound if there's a discrepancy.