Most people have two kidneys, one on each side of the spine under the lower ribs. They are bean-shaped organs about the size of a clenched fist
. The kidneys filter waste products from the blood, produce urine, help regulate blood pressure, balance body fluids, and perform other vital functions
. Although having two kidneys is typical, humans can live with just one kidney. Some people are born with only one kidney or may have one removed due to injury or donation. One healthy kidney can enlarge and compensate by performing up to 75% of normal kidney function, allowing a person to live a normal life with careful health management
. In summary, humans normally have two kidneys, but it is possible to live well with only one. The presence of two kidneys provides redundancy and extra functional capacity for the body's needs
