Q. How is the size of the driver on my loudspeaker determined?
Answer:
Speaker driver diameters are traditionally expressed in inches and standard sizes, say 4, 5, 6.5 and 8 inches. They are all approximations and one chooses the nearest standard size when describing them in specifications. In measuring them you would certainly include all of the surround, which contributes to the sound you hear and many driver manufacturers include the bezel as it is part of the driver and some measure between the fixing holes.