One of my favorite things about pianos is the amazing range of types and sizes on offer. There’s no other 
musical instrument with such diversity, and what it means is that there truly is a piano to fit anyone’s lifestyle.
Grand pianos, especially, come in a huge range of sizes. A grand can be anywhere from under 5 feet long, to 10 feet or more. Generally speaking, the larger the piano, the bigger and more impressive the sound, but even a small grand will still produce great music.
So, we wanted to put together a guide to the different sizes of grand pianos that are available. However, one note before we get started: there’s no true standardization in piano sizes. These terms are really just for reference, as individual manufacturers may or may not use them in their naming, and there’s quite a lot of disagreement on where the exact size cutoff points are.
Baby
A baby grand piano is one of the most popular sizes, especially for people wanting a grand piano in their home. These start at 5 feet, and go up to around 5’6". Despite their relatively small size, most of the major manufacturers make these. Some good examples include Yamaha’s G series and the Steinway Model S. If you want a piano for your home, baby grands are a great place to start.
Medium
Medium grands are slightly larger than a baby grand, generally between 5’7" and 5’10" or so. This is the size at which you start getting "true" grand piano sound, thanks to the larger interior space. The Steinway Model M is a perfect example of a Medium grand piano, capable of full-sized sound and yet still small enough to fit into a typical house.
Parlor
Again, moving upwards in size, parlor grand pianos are generally in the area of 6 feet, give or take a couple inches. Sometimes a piano that’s exactly 6 feet is also called a "Professional Grand." The Kawai RX-3 BLAK is a popular example of this size piano. Also, as the name suggests, the larger the piano gets, the bigger the room needs to be to hold it.
Ballroom
As the name implies, these large pianos – which are also sometimes known as "Semiconcert Grands" are meant to fill a big room, although still one within a home. Most ballroom grand pianos are around 7 feet long, and can get into 8-foot territory as well. Kawai makes an excellent ballroom grand, the RX7.
At this point, you’re into the territory of true performance instruments. While smaller pianos are still great for entertaining people, this is the size range you should start looking at if you’re a performer looking to fill a room with sound.
Concert
The largest and most prestigious grand pianos are the concert grands. These are at least 9 feet long, up to at least 10"2′ for the Fazioli F308. A grand of this size can easily fill the largest concert halls, and can have unmatched range and expressive qualities. As the biggest, they are also the most expensive pianos, but the sound is simply unmatched.
So, with six (or arguably seven) different "official" sizes of piano, there truly is one for every home.
Do you think there should be more standardization in piano sizes and the terminology used?