Pregnancy Week Calculator
How many weeks pregnant are you? Enter your last menstrual period date or your due date to find out your exact gestational age in weeks and days.
How the Pregnancy Week Calculator Works
This calculator determines how far along you are in your pregnancy by counting the days between your last menstrual period (LMP) and today's date. The total days are converted into weeks and remaining days.
From LMP
When you enter your LMP date, the calculator counts the exact number of days from that date to today. This is divided into complete weeks plus remaining days. For example, 171 days equals 24 weeks and 3 days.
From Due Date
If you know your due date, the calculator works backwards. Since a full-term pregnancy is 280 days from LMP, it subtracts 280 days from your due date to estimate your LMP, then calculates forward to today.
Trimester Breakdown
Pregnancy is divided into three trimesters: weeks 1-12 (first), weeks 13-26 (second), and weeks 27-40 (third). Each trimester marks important developmental milestones for your baby.
Frequently Asked Questions
How do I calculate how many weeks pregnant I am?▾
Pregnancy weeks are counted from the first day of your last menstrual period (LMP), not from conception. To calculate, count the number of days from your LMP to today, then divide by 7. The result gives you your weeks and remaining days.
Why is pregnancy counted from the last period and not conception?▾
Pregnancy is dated from the LMP because most women know when their last period started, but the exact conception date is often unknown. By medical convention, gestational age begins about two weeks before actual conception typically occurs.
What are the three trimesters of pregnancy?▾
The first trimester spans weeks 1-12, the second trimester covers weeks 13-26, and the third trimester runs from week 27 until birth (around week 40). Each trimester brings different developmental milestones and physical changes.
Is it normal to deliver before or after 40 weeks?▾
Yes. A full-term pregnancy is considered 37-42 weeks. Only about 5% of babies arrive on their exact due date. Most babies are born between 38 and 41 weeks, which is completely normal.
Medical Disclaimer
This calculator is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider for medical decisions regarding your pregnancy.