How many pairs of ribs do humans have?

Humans usually have 12 pairs of ribs, for 24 ribs altogether.

The rib cage protects the heart, lungs, and other organs in the thorax while also helping the chest expand during breathing. Each pair attaches at the back to one of the 12 thoracic vertebrae. Most ribs connect toward the front through costal cartilage.

The first seven pairs are called true ribs because each connects directly to the sternum. Pairs eight through ten are false ribs because they connect indirectly through the cartilage above. The eleventh and twelfth pairs are floating ribs: they attach to the spine but have no front attachment to the sternum.

“Usually” matters because anatomical variation exists. Some people have an extra cervical rib near the neck, while others may have unusual rib development or, rarely, a missing rib. These exceptions do not change the standard answer used in general human anatomy: 12 pairs.