How Many Weeks Pregnant Am I?
Pregnancy weeks are usually counted from the first day of your last menstrual period, not from conception. By the time many people miss a period, they may already be considered about 4 weeks pregnant.
How to calculate pregnancy week by LMP
Find the first day of your last menstrual period. Count the number of weeks from that date to today. That number is your estimated pregnancy week.
Example: LMP March 1, today April 12 → about 6 weeks pregnant.
How to calculate pregnancy week by due date
If you know your due date, count backward. Pregnancy is generally dated as 40 weeks from LMP, so a pregnancy week calculator can do the math automatically.
Why weeks pregnant may change
Your healthcare professional may adjust your pregnancy week after an early ultrasound, especially if your cycle is irregular or LMP is uncertain.