Pregnancy Calculator
Use this pregnancy calculator to see how many weeks pregnant you are today, your trimester and your estimated due date.
What Is a Pregnancy Calculator?
A pregnancy calculator tells you how far along you are, which trimester you are in and when your baby is likely to arrive. Enter the first day of your last menstrual period (LMP) and your usual cycle length. The tool counts the days from your LMP to today and shows your current week of pregnancy.
How Pregnancy Weeks Are Counted
Doctors count pregnancy from the first day of your last period, not from the day of conception. That is why you are already about two weeks pregnant at conception. A full pregnancy lasts about 40 weeks, or 280 days. If your cycle is longer or shorter than 28 days, the calculator adjusts your due date to match.
The Three Trimesters
- First trimester: weeks 1 to 13. Early development, and many people experience nausea and fatigue.
- Second trimester: weeks 14 to 27. Energy often returns, and many parents feel the first movements.
- Third trimester: weeks 28 to birth. The baby gains weight and prepares for delivery.
Weeks Pregnant Today and Days Left
The results show your weeks and days pregnant, how many days remain until your estimated due date and the approximate date of conception. They also show when full term begins at 37 weeks.
How Accurate Is a Pregnancy Due Date?
A due date is an estimate. Only about 4 to 5 percent of babies are born on their exact due date, and most arrive within a couple of weeks before or after it. An early ultrasound is often used to confirm dating, especially when periods are irregular.
What to Do After You Find Out You Are Pregnant
Schedule a first prenatal appointment, start a prenatal vitamin with folic acid if your provider recommends it and ask about medicines, foods and activities to avoid. Keep track of appointments and screening tests throughout each trimester.
Frequently Asked Questions
How many weeks pregnant am I?
Enter your last period date above and the result shows your weeks and days pregnant today.
Can I use this if my periods are irregular?
You can, but results may be less accurate. Ask your provider about an ultrasound for dating.
How is this different from a due date calculator?
This tool focuses on your current progress. Our Due Date Calculator also supports conception date and IVF transfer dates.
Estimates only. Your healthcare provider confirms your due date, often with an early ultrasound.