Cone Area Calculator
Compare subwoofer configurations by total cone area. Answer the classic "6 12s vs 3 18s" debate!
Nominal size overstates radiating area ~30-40% for car subs. A "12-inch" sub's real datasheet Sd is closer to a 10" circle — the wide surround eats into the cone, and high-excursion subs lose even more. Best: enter your driver's datasheet Sd per card for exact area. No datasheet? Toggle Effective Sdfor an approximate car-audio correction (fallback factors ~0.71 at 12", ~0.65 at 15-18").
ASetup A
6× 12" Subwoofers
Have your driver's Sd? Enter it for exact area — overrides nominal size and the Effective Sd estimate.
BSetup B
3× 18" Subwoofers
Have your driver's Sd? Enter it for exact area — overrides nominal size and the Effective Sd estimate.
Comparison Results
3× 18" has 11.1% more cone area than 6× 12". More cone area generally means more air movement potential, but other factors like power handling, enclosure design, and driver quality also matter significantly.
Cone Area Reference
| Size | Area (1×) | Area (2×) | Area (4×) | Area (6×) |
|---|---|---|---|---|
| 7" | 33.2 in² | 66.4 in² | 132.7 in² | 199.1 in² |
| 8" | 50.3 in² | 100.5 in² | 201.1 in² | 301.6 in² |
| 10" | 78.5 in² | 157.1 in² | 314.2 in² | 471.2 in² |
| 12" | 113.1 in² | 226.2 in² | 452.4 in² | 678.6 in² |
| 15" | 176.7 in² | 353.4 in² | 706.9 in² | 1060.3 in² |
| 18" | 254.5 in² | 508.9 in² | 1017.9 in² | 1526.8 in² |
| 21" | 346.4 in² | 692.7 in² | 1385.4 in² | 2078.2 in² |
| 24" | 452.4 in² | 904.8 in² | 1809.6 in² | 2714.3 in² |
Why Cone Area Matters
The Basics
Sd (cone area) measures the radiating surface of a driver—the part that actually pushes air. Basic circle math: A = π × r²
Air Movement = SPL
Larger surface area can move more air per stroke. That air displacement creates the pressure waves you feel. But area alone doesn't tell the whole story—motor strength, enclosure tuning, and excursion capability all factor into real-world output.
The Eternal Argument
Six 12s versus three 18s—every audio forum has this thread. The numbers: 6× 12" = 678.6 in², 3× 18" = 763.4 in². Real-world factors like trunk space, enclosure volume, and budget usually settle the debate.
Don't Forget Excursion
Total air displacement combines area with throw: Vd = Sd × Xmax. A compact driver with serious excursion can match a bigger cone with shorter travel.
Nominal vs. effective Sd:Manufacturer Sd specs use the effective piston area, which is smaller than what the nominal diameter suggests. A "12-inch" driver typically has Sd closer to a 10.5-11" circle due to the surround. For precise Vd calculations, use the Sd from your driver's datasheet rather than nominal size.