How many weeks pregnant am I?
Enter the first day of your last menstrual period and see exactly how many weeks and days pregnant you are right now, which trimester you are in, your estimated due date, how far along you are on the 40-week timeline and how big your baby is this week.
Your dates
First day of your last menstrual period.
Today's date or the date you want to check.
Pregnancy is counted from the first day of your last period, not from conception. A full-term pregnancy is 40 weeks (280 days). Change the current date to see where you were, or will be, on any day. Results update as you type.
What this week means
Where you are on the 40-week timeline
Milestone dates for your pregnancy
Development week by week
Each row shows the approximate date you reach that week, the typical baby size comparison and what is developing. The highlighted row is the closest to where you are right now.
| Week | Approx. date | Baby size | What is developing |
|---|
Pregnancy weeks, explained
How Pregnancy Weeks Are Counted
Pregnancy is counted from the first day of your last menstrual period (LMP), not from conception. This means you are technically "pregnant" for about two weeks before conception actually occurs. A full-term pregnancy is 40 weeks (280 days) from the LMP. This standard dating system is used worldwide by obstetricians and midwives to track fetal development and schedule prenatal care.
Understanding Trimesters
Pregnancy is divided into three trimesters. The first trimester (weeks 1-12) involves rapid cell division, organ formation, and the highest risk of miscarriage. The second trimester (weeks 13-27) is often called the "golden period" as morning sickness usually subsides and the baby grows significantly. The third trimester (weeks 28-40) involves final organ maturation, weight gain, and preparation for birth.
Baby Size Milestones
Baby size comparisons help visualize growth: at 8 weeks the embryo is the size of a raspberry, at 12 weeks a lime, at 20 weeks a banana, at 24 weeks an ear of corn, at 28 weeks an eggplant, at 32 weeks a squash, at 36 weeks a honeydew melon, and at 40 weeks a small watermelon. These comparisons are approximate and based on average fetal measurements.
Common questions
Why does pregnancy start from the last period, not conception?
The exact date of conception is usually unknown because sperm can survive up to 5 days in the reproductive tract. The first day of the last menstrual period is a reliable, observable date that most women can identify. Ovulation typically occurs around day 14 of a 28-day cycle, so gestational age is approximately 2 weeks longer than the actual fetal age.
What is the due date and how accurate is it?
The estimated due date (EDD) is 40 weeks (280 days) from the first day of the last menstrual period. Only about 5% of babies are born on their exact due date. Most healthy births occur between weeks 37 and 42. First-time mothers tend to deliver slightly past their due date on average.
When does each trimester start and end?
The first trimester spans weeks 1 through 12, the second trimester weeks 13 through 27, and the third trimester weeks 28 through 40. Some sources define slightly different boundaries, but these are the most commonly used divisions in clinical practice.
How big is the baby at 20 weeks?
At 20 weeks (the halfway point), the baby is approximately 6.5 inches long from crown to rump and weighs about 10.6 ounces. This is roughly the size of a banana. By this stage, the anatomy scan can reveal the sex, and the mother typically begins feeling fetal movements (quickening).
This calculator gives an estimate, not a medical diagnosis. LMP-based dating assumes a 28-day cycle and can be off by two weeks or more, especially with irregular cycles. Only about 5% of babies arrive on their exact due date. Your precise gestational age and due date are determined by your gynecologist or obstetrician, usually with an early ultrasound. Always follow the guidance of your prenatal care provider, and seek immediate care for heavy bleeding, severe pain or decreased fetal movement.