Grand pianos are larger than regular pianos due to having some varied characteristics.  Regular sized grand pianos are usually played at open concerts.

This variety of piano is larger since the frame and the strings are placed in a horizontal way, extending away from the keyboard.  In order to obtain good resonance, it is better to place it in a spacious area with elevated roofing.

Manufacturers make different sizes of grand pianos, according to the use it will have.  The concert grand piano is approximately 7 ft 1 in to 9 ft 10 in, over a foot longer in average than the parlor piano, used more at homes or small areas.

The longer the piano, the less likely it is to have inharmonicity and the better the sound will be.