Virtually all pianos have 88 keys.

However, Pleyel*, a company established in Paris, France and founded in 1807 once built a double grand (2 pianos in 1 case) with a keyboard at each end - hence, 176 keys.

Bosendorfer makes the Imperial Concert Grand which features 96 notes (8 extra keys in the bass).

Some pianos have 54 or 66 keys, one of these was known as "Tom Thum" (made by Kohler & Campbell) and the other was "Cameo", made by Melodigrand and controlled by the Winter Piano Co. Many of the action parts in these small pianos were actually true to form, with the exception of the hammers.

*Pleyel is now under a cooperative contract with Schimmel Piano Co

*Bosendorfer is now controlled by Kimball International