How thick should bass traps be?

On the strict on-axis quarter-wave rule (depth = c ÷ 4f), absorbing down to 100 Hz needs about 85 cm of total depth (343 ÷ 100 ÷ 4 = 0.86 m); 80 Hz needs about 107 cm. Note that this calculator's default Effectiveness Factor of 0.5 reports a lower "Effective From" figure than that strict depth implies — that is deliberate, because real-room incidence is not purely on-axis, so in practice you can roughly halve the on-axis quarter-wave depth. For practical home studios, 10–15 cm absorbers with 5–10 cm air gaps target frequencies from about 150 Hz up. Corner mounting effectively increases the depth.

Does corner mounting help?

Yes, significantly. A room corner is where the pressure maxima of all three axial-mode families (length, width, height) converge, so it is where low-frequency energy is densest. A porous absorber is a velocity-driven device, so the gain is not from sitting at a pressure peak — it comes from the geometry: straddling a corner roughly doubles the sound path length through the panel and lets you stack much greater depth (and air gap) than a flat wall allows, both of which push the effective absorption lower in frequency.

What material should I use?

Mineral wool (Rockwool, Knauf) with a density of 40-80 kg/m³ is the most cost-effective. Higher density is not necessarily better — 60 kg/m³ is often optimal. Standard acoustic foam is effective above 500 Hz but poor at bass frequencies due to insufficient depth and density.

How many bass traps do I need?

Start with all four vertical corners floor to ceiling. This is the most impactful treatment. Add horizontal corners (wall-ceiling, wall-floor) for further improvement. A typical home studio benefits from 8-12 bass trap panels. More is generally better for low frequencies.

AudioCalcs

Bass Trap Calculator — Porous Absorber Dimensions

Calculate bass trap dimensions and effective absorption range for room corners.

Absorber Thickness

Depth of the porous panel (mineral wool 50–150 mm typical)

Air Gap Behind

Air cavity behind the panel — a larger gap lowers the minimum absorbed frequency

How We Calculate This

Quarter Wavelength Rule

Effective frequency = c / (4 × total depth)

Where c = 343 m/s and total depth = absorber thickness + air gap. The absorber is most effective at the frequency whose quarter wavelength equals the total depth.

Practical Range

The Effective From figure applies the Effectiveness Factor (default 0.5) to the quarter-wavelength frequency, reflecting the fact that real-room sound arrives at angles rather than purely on-axis. A porous absorber has no upper cutoff: above this frequency it keeps absorbing with steadily increasing effectiveness through the mid and high frequencies.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard formulas. Always verify results for critical applications.