How Many Weeks Pregnant Are You? | Free Due Date Calculator

Wondering how far along you are in your pregnancy? Knowing the number of weeks pregnant is essential for tracking fetal development, planning appointments, and understanding what to expect each trimester. Our Due Date Calculator makes it simple to find out exactly how many weeks pregnant you are and estimate your due date accurately.

Why Knowing Your Pregnancy Weeks Is Important

• Medical Care: Helps schedule prenatal checkups, scans, and tests at the right time.
• Development Tracking: Understand your baby’s growth and milestones.
• Planning: Prepares you for maternity leave, birthing classes, and baby essentials.
• Peace of Mind: Know your stage and manage your pregnancy more confidently.

How We Calculate Pregnancy Weeks

Pregnancy is measured from the first day of your last menstrual period (LMP), not the day of conception. The formula is simple:

Weeks Pregnant = Current Date − First Day of Last Menstrual Period (LMP)

• Count the number of days between today and your LMP.
• Divide by 7 to get the total weeks.
• The result gives your current week of pregnancy.

Estimated Due Date Formula

The standard formula to estimate your due date is called Naegele’s Rule:

Due Date = First Day of LMP + 280 days (40 weeks)

• This assumes a 28-day menstrual cycle.
• Adjustments can be made for shorter or longer cycles.

Step-by-Step Example: Calculate Weeks Pregnant

Problem: Your LMP was on January 1, 2025, and today is March 15, 2025.
Step 1: Calculate days between dates: January 1 → March 15 = 73 days.
Step 2: Divide by 7 to get weeks: 73 ÷ 7 ≈ 10.4 weeks.
Solution: You are 10 weeks and 3 days pregnant.

Step-by-Step Example: Calculate Due Date

Problem: LMP is January 1, 2025.
Step 1: Add 280 days to the LMP: January 1 + 280 days = October 8, 2025.
Solution: Estimated due date is October 8, 2025.

How the Due Date Calculator Works

1. Enter the first day of your last menstrual period (LMP).
2. The calculator computes the number of days from your LMP to today.
3. It converts the days into weeks and days to show how far along you are.
4. It also adds 280 days to your LMP to estimate your expected due date.

FAQs – Pregnancy Weeks & Due Date Calculator

1. How accurate is the due date calculator?
It provides an estimate based on your LMP. Ultrasounds can provide more precise dating.

2. What if my menstrual cycles are irregular?
The calculator uses a standard 28-day cycle. Adjustments may be needed for irregular cycles.

3. Can I use it if I don’t know my exact LMP?
If unsure, use the date of ovulation or first positive pregnancy test, but accuracy may decrease.

4. Does it account for leap years?
Yes, the calculator automatically accounts for leap years.

5. Can I calculate past pregnancies?
Yes, you can enter any past LMP date to see weeks and due date.

6. How do I know my trimester?
First trimester: 1–12 weeks, second: 13–26 weeks, third: 27–40 weeks.

7. Does it replace medical advice?
No, always consult your healthcare provider for prenatal care.

8. Can I track weekly changes?
Yes, using the calculator each week shows your updated pregnancy progress.

9. Can it predict the exact day I will deliver?
No, the due date is an estimate. Most babies are born within ±2 weeks of the due date.

10. Is it free and online?
Yes, the calculator is free, fast, and works in any browser.