How many bars on a xylophone?

The xylophone is a percussion instrument consisting of a row of bars of graduating lengths suspended over metal tubes, called resonators, and set in a wooden or steel frame. As on a piano, the playing structure of the xylophone is called a "keyboard." The musician plays the instrument by striking the "keys" (bars) with phenolic (resin), plastic or rubber mallets.

If your 'xylophone' has 'steel' bars, it might, instead, be a mellophone.

The Word "xylophone" comes from the Greek "xylon" (wood) and "phone" (voice); the literal translation is "wooden sound." For this reason, classic western xylophones have rosewood keyboards (some modern western xylophones and student-quality instruments have synthetic or fiberglass-coated plastic keys) of 2.5 - 4.0 octaves, which means the number of "bars" on the keyboard varies. An octave consists of 8 notes (keys), so a 2.5 octave keyboard will have 20 keys, while a 4.0 octave keyboard will have 32. Concert xylophones are typically 3.5 to 4.0 octaves.

The Glockenspiel (sometimes called bells), looks a lot like a xylophone, but uses steel bars instead of wood, and produces a brighter sound. A glockenspiel has 30 keys, set in two rows.