What Is the Normal Kidney Size in Millimeters?

The length of a healthy adult kidney is usually about 90 to 120 millimeters (9 to 12 centimeters). This size is reported on ultrasound or CT scan, and small differences between people, such as 85 or 125 millimeters, are usually normal and not a cause for concern.

Kidney size in each person depends on factors such as age, sex, and body build. In taller or larger-built people, the kidneys are slightly larger; in children, they are naturally smaller. Below, we explain in more detail what normal kidney size is in millimeters for men and women at different ages.

If the kidneys become smaller than the normal range, this may be due to reduced function or may indicate chronic disease. Larger kidneys can also be related to issues such as cysts, inflammation, or obstruction. In addition, a length difference of up to about 2 centimeters between the left and right kidney can be normal.

An important point to keep in mind is that if your imaging report says your kidney size is outside the normal range, you should not self-diagnose or self-medicate.

Accurate interpretation requires a complete evaluation by a urologist or nephrologist. The doctor considers symptoms, blood and urine tests, and the overall clinical picture to decide whether the current kidney size is a sign of disease.