Speaker Fit Calculator
A hole is the one decision you cannot undo. Trade names like 6.5-inch and 6x9 are tooling names inherited from a panel, not measurements of anything — the four figures that decide whether a unit bolts in are cutout diameter, flange outer diameter, mounting depth and the flat area around the opening. Measure yours, put the box’s claims next to them, and find out now rather than with the trim off.
Units you measured in
What you measured on the panel
Across the opening itself, not the trim ring.
Widest circle of flat panel the flange can land on.
Panel face to the first obstruction — glass, linkage, bracing.
What the box claims
Leave blank if the spec sheet omits it — most do.
Flange underside to the deepest point of the magnet.