How many pairs of ribs does the typical adult human have?

How to get close to this number

Count them on yourself, or count the vertebrae. Ribs attach to the thoracic vertebrae, one pair each, and the thoracic spine has a dozen segments. Reconstructing from the spine is more reliable than trying to count ribs by touch, since the lower ones are hard to feel.

The myth in the explanation is worth addressing directly because it is extremely persistent: men do not have one fewer rib than women. The claim comes from a reading of Genesis and has never been anatomically true, and a single glance at any medical imaging settles it. It is a good example of a belief that survives because almost nobody has occasion to check.

Individual variation is real, though, just not along that axis. A small percentage of people are born with an extra cervical rib on one or both sides, and occasionally someone has a pair fewer. As with the total bone count on this site, the standard figure describes a typical adult rather than a universal constant.