The ribs end at the costal cartilage in the front of the chest; the lower edge of the rib cage is usually felt around ribs 10–12, with ribs 11 and 12 being the floating ribs that do not attach to the sternum.

Anatomy

The rib cage has 12 pairs of ribs, and most of them curve from the spine around to the front of the torso.

Ribs 1–7 attach directly to the sternum, ribs 8–10 attach indirectly through cartilage above them, and ribs 11–12 end without a front attachment.

If you meant “where does the liver start?”

The liver sits under the right lower ribs, mostly behind the right costal margin, so people often confuse its position with the rib line.

That means the ribs do not “turn into” the liver; they sit above and partly protect it.

Tiny correction

Your title looks like it may have a typo: “lier” probably means “liver.”