The size of a normal kidney is 10 to 12 centimeters long, 5 to 6 centimeters wide, and about 3 to 4 centimeters thick. Normal human kidneys come in pairs, one on each side, with the left kidney slightly larger than the right, and the left kidney positioned 1 to 2 centimeters higher than the right. The kidneys work together to ensure the smooth elimination of metabolic wastes from the body, as well as maintaining the body’s water and electrolyte balance, which is essential for maintaining blood pressure and preventing anemia. When the size of the kidneys is far below the normal range, it may indicate that the patient has renal atrophy, which is common in uremia and other serious diseases; when the size of the kidneys is larger than normal, it indicates that the patient may have pyelonephrosis and other diseases. Therefore, when a patient’s physical examination reveals that the size of kidney is not in the normal range, he should consult a doctor in time to investigate the cause of the disease and avoid delaying the treatment.