Grands and pianos are classified depending on their sizes:

Baby grands - less than 5`8`` (173cm)

Grands - 5`8`` - 8`10`` (173-269cm)

Concert grands - over 8`10`` (269cm)

Uprights:

Spinets - less than 38`` (97cm)

Consoles - 38``- 44`` (97-112cm)

Studios - 44``- 51`` (112-130cm)

Full size or professional - taller than 51`` (130cm)

For more accuracy each brand name piano has own model designation. It could be only a letter or letters, a number or combination of letter and number.

Note: Spinets and consoles were introduced in 1930