For a sedan, one sub, 300 W. It’s the same math as the designer’s step-by-step mode, where you can fit the box to your space, vehicle and amp and get plans, a cut sheet and DXF.
Sealed Ported · SPL in dB at 1 W / 1 m, no cabin gain
Thiele/Small parameters
Fs
26.6 Hz
Qts
0.52
Qes
0.554
Qms
8.73
Vas
2.54 ft³
Re
2.21 Ω
Sd
81.4 in²
Xmax
0.45″
Vd
36.5 in³ calc.
Mms
195 g calc.
BL
11.4 T·m calc.
EBP
48 — suits sealed calc.
Sensitivity, 1 W / 1 m
85.9 dB calc.
General
Size
12″
Voice coils
2 Ω
RMS power
300 W
Mounting dimensions
Cutout diameter
11 1/16″
Mounting depth
5 3/8″
Overall diameter
12 1/2″
Magnet diameter
5 1/4″
“≈” means the value isn’t in the spec sheet and a typical value for the size is used; “calc.” means it’s calculated from the published parameters. Check the manufacturer’s spec sheet before you build.