The baby grand introduced grand piano sound into small homes and apartments. With a keyboard as wide as a standard grand but an overall length downsized nearly four feet, it weighs almost half as much as a full-sized concert model. The single definitive measurement used to size a grand piano is the length from the edge of the keyboard back to the piano's tail. While this dimension varies among different manufacturers, typical baby grand lengths range from 4 feet, 11 inches to 5 feet, 6 inches.
Close the lid of the piano.
Instruct an assistant to hold one end of a measuring tape at the tail of the piano. The grand piano's tail is the tip of the smaller, rounded extremity of the piano's case, at the furthest point behind the keyboard.
Stretch the tape over the lid and align it with the front edge of the keyboard, approximately at the location of the middle C key. Counting from the left side of the keyboard, middle C is the 40th key.
Read the measurement off the tape.