At 11 weeks of pregnancy, a fetus measures roughly 42 to 53 millimeters from crown to rump, or just over 1.5 to 2 inches. That’s about the size of a fresh fig. Weight at this stage is approximately a quarter of an ounce, or around 7 grams. While those numbers sound tiny, they represent explosive growth from just a few weeks earlier, and the fetus is in the middle of a major developmental sprint.
Crown-to-Rump Length Through Week 11
Fetal size is measured from the top of the head to the bottom of the torso (not including the legs) during the first trimester. This crown-rump length, or CRL, is the single most accurate way to date a pregnancy on ultrasound. At the start of week 11, the measurement sits around 42 mm. By the end of the week, at 11 weeks and 6 days, it reaches roughly 53 mm. That’s nearly a centimeter of growth in just seven days.
To put it in familiar terms, the fetus goes from the length of a large grape to the length of a fig over the course of this one week. If your ultrasound measurement falls a few millimeters above or below these numbers, that’s normal. Individual variation is expected, and your provider uses the CRL primarily to confirm your due date rather than to flag a problem.
What an 11-Week Fetus Looks Like
By week 11, the fetus is starting to look more recognizably human, though proportions are still unusual. The head makes up roughly half the total body length at this point, but the body is catching up fast. Fingers and toes, which were webbed just a couple of weeks ago, are now separating into individual digits. Tiny fingernails have formed. Miniature ears are visible on the sides of the head.
The skin is still translucent, meaning internal structures like developing blood vessels are visible beneath the surface. Bones are beginning to harden, replacing the softer cartilage that formed the early skeleton. The face has developed enough that the eyes, nose, and mouth are all in their correct positions, though the eyelids are fused shut and will stay that way for several more weeks.
Movement You Can See but Not Feel
One of the most striking things about an 11-week ultrasound is how much the fetus moves. It kicks, stretches, does somersaults, and waves its hands, sometimes almost constantly during a scan. This level of activity often surprises parents who assume the fetus is mostly still at this stage.
You won’t feel any of this yet. The fetus is simply too small, and there’s too much cushioning from amniotic fluid and uterine tissue. Most people don’t start noticing fetal movement until somewhere between 16 and 22 weeks, with first-time parents typically feeling it later in that window. But if you have an ultrasound at 11 weeks, you’ll likely see the movement on screen in real time.
What’s Developing on the Inside
Week 11 falls near the end of a critical period called organogenesis, when all the major organ systems are being established. By this point, the heart has been beating for several weeks and has divided into four chambers. It’s pumping blood through a growing network of vessels. On ultrasound, your provider will check for cardiac activity, which is clearly visible and often audible by now.
The kidneys are beginning to produce small amounts of urine, which gets released into the amniotic fluid. The liver is large relative to the rest of the body and has started making blood cells, a job it will hand off to the bone marrow later in pregnancy. The intestines, which temporarily bulged into the umbilical cord as they grew, are starting to migrate back into the abdominal cavity. The diaphragm is forming, separating the chest from the abdomen.
The brain is developing rapidly, producing neurons at an extraordinary rate. The two hemispheres are now distinct, and the basic structure of the nervous system is in place, which is why reflexive movements like kicking and grasping are already possible even though they’re entirely involuntary at this stage.
How Week 11 Compares to Surrounding Weeks
Growth during the first trimester is fast enough that even a week or two makes a noticeable difference. At 9 weeks, the fetus measures around 23 mm, roughly the size of a cherry. By 11 weeks it has nearly doubled. By 13 weeks, it will reach about 70 to 80 mm, or just over 3 inches, closer to the size of a lemon. Weight follows a similar curve: the quarter-ounce fetus at 11 weeks will weigh a full ounce by the end of the first trimester, just two weeks later.
This rapid scaling is why first-trimester ultrasound dating is so precise. A difference of just a few millimeters in crown-rump length corresponds to only a day or two of gestational age, making it far more accurate than dating based on the last menstrual period. If your provider adjusts your due date after an early ultrasound, the CRL measurement is the reason.