The largest commonly used woodwind instrument is the Contrabassoon.
The tuba is the largest brass instrument with the largest mouthpiece. In marching the Sousaphone and the Contrabass bugle (known as contra) are marching versions of the tuba. The contra is the lowest-pitched, largest, and heaviest marching instrument.
A Cello is the worlds largest instrument. If im wrong, please improve this answer and leave a comment bellow. :)
So that the sound can be heard louder
The tuba is the largest and the lowest tone brass instrument
The tuba is the largest brass instrument with the largest mouthpiece. In marching the Sousaphone and the Contrabass bugle (known as contra) are marching versions of the tuba. The contra is the lowest-pitched, largest, and heaviest marching instrument.
The cello is the largest of the three instruments.
Contras Sax
The cello.
cello
basoon
The Double Bass.