A human typically has two kidneys , one on each side of the spine under the lower ribs. These kidneys are bean-shaped organs, each about the size of a clenched fist, and they function primarily to filter the blood, remove waste, and produce urine.

While most people have two kidneys, there are rare cases where humans can have more than two, such as four kidneys due to supernumerary kidneys, but this is very uncommon.