How big is a fetus at 9 weeks of pregnancy?

At nine weeks of gestation, the embryo has transitioned into the fetal stage and is now referred to as a fetus. Its crown-rump length (CRL)—measured from the top of the head to the bottom of the buttocks—is typically approximately 2.2 to 2.5 centimeters (about 0.87 to 0.98 inches), roughly the size of a grape or a medium-sized olive.

During this critical period of organogenesis, major structures are rapidly maturing: the heart is fully formed and beating at about 140–170 beats per minute, detectable via transvaginal ultrasound; limb buds have developed into recognizable arms and legs with distinct hands and feet (though fingers and toes may still be webbed); the brain is undergoing rapid growth and differentiation; and facial features—including eyes, nostrils, and the beginnings of ears—are becoming more defined. The placenta is also increasingly functional, taking over hormonal support from the corpus luteum.

It’s important to note that fetal size can vary slightly based on maternal factors (e.g., ethnicity, BMI, parity), gestational dating accuracy (especially if based on last menstrual period rather than early ultrasound), and individual genetic variation. A first-trimester ultrasound remains the gold standard for confirming gestational age and assessing fetal viability and anatomy.