Truck sub box guide: behind-seat and under-seat boxes
Trucks have bass-friendly cabins but very little room for a box. Here is how cab type, measurements and subwoofer choice decide what fits.
Behind the seat or under it
Behind-seat boxes sit between the seat back and the rear wall. Common in regular and extended cabs, and in crew cabs with the rear seat folded. Depth is the limit, so shallow-mount subwoofers and thin, tall boxes are typical.
Under-seat boxes sit under a crew cab’s rear bench and often fire down or forward. They keep the seats usable but have the least volume, so they suit compact, sealed designs.
Your cab type matters
Regular cab, extended cab (SuperCab, Double Cab, Quad Cab) and crew cab (SuperCrew, CrewMax, Crew Cab) trucks of the same model have very different spaces. Always tell us the year range and the cab type; a box made for one rarely fits another.
How to measure
Width at the top and at the floor, since cab walls taper.
Height from the floor to where the seat back meets the box, with the seat where you drive it.
Depth at the floor and at the top: the seat back is angled, so these differ.
Anything in the way: jack and tool kits, factory amplifiers, seat brackets, wiring, vents.
Photos of the space with a tape measure in frame help us more than any description.
Vehicle-specific or universal?
A vehicle-specific box is shaped for one truck and cab, uses the space fully and installs cleanly, but only fits that vehicle. A universal box is cheaper and portable between vehicles, but usually gives up air space or seat position in a truck. In most trucks, a vehicle-specific or custom box is the better result.
Choosing the subwoofer
Check mounting depth first: it must clear the inside depth of the box. Then check that the sub’s recommended sealed volume is achievable in the space. Shallow subwoofers are designed for exactly this job.
