Weeks Pregnant Calculator
Find out exactly how many weeks pregnant you are based on your last menstrual period. See your current trimester and days remaining until your due date.
Part of our Health Calculators collection.
Weeks Pregnant Calculator
Free online calculator
Results update automatically as you type
How to Use This Calculator
- 1
Enter the first day of your last menstrual period.
- 2
See how many weeks and days pregnant you are today.
- 3
Find out which trimester you're in and your estimated due date.
How Pregnancy Weeks Are Counted
Weeks Pregnant = Days since LMP / 7 Pregnancy is measured from the first day of your last menstrual period (LMP), not from conception. This means you're counted as 'pregnant' for the 2 weeks before you actually conceive.
Example Calculation
Example: LMP was 10 weeks ago
Inputs
lmpDate: 2025-02-06
Result
10 weeks, 0 days pregnant — Second trimester approaching
10 weeks from February 6 = approximately April 17, 2025. Due date ~November 13, 2025.
Frequently Asked Questions
Why does pregnancy start before conception?
Doctors count pregnancy from your last period because it's a known date. Conception happens about 2 weeks later. So at '4 weeks pregnant', you conceived about 2 weeks ago.
When should I have my first prenatal appointment?
Most doctors schedule the first appointment between 8 and 12 weeks. If you have risk factors or fertility treatments, you may be seen earlier.