Soundproofing Material Calculator

Calculate sound transmission loss using the mass law (TL = 20×log10(f×m) - 47 dB). Supports single and multi-layer assemblies with air gaps.

Inputs

Surface mass per layer (kg/m²)

Frequency (Hz)

Number of layers

Air gap between layers (mm)

Tab to move between fields

Results

Transmission loss (dB)

26.7

Mass law TL (dB)26.7

Estimated STC (lab)27

Estimated field STC22

Total surface mass (kg/m²)10

Est. coincidence freq (Hz)1,016

How to Use This Calculator

Enter Surface mass per layer (kg/m²), Frequency (Hz), and Number of layers.
Set Air gap between layers (mm).
Review the Transmission loss (dB) result.
Use Mass law TL (dB) and Estimated STC (lab) to inform your decision.

How the result changes with Surface mass per layer (kg/m²)

Surface mass per layer (kg/m²)	Transmission loss (dB)
50	40.7
175	51.5
325	56.9
450	59.7

What each input means

Surface mass per layer (kg/m²): Mass per unit area of each panel/layer. Drywall (5/8") ≈ 11 kg/m², 4" concrete ≈ 195 kg/m².
Frequency (Hz): Sound frequency for transmission loss calculation. Mass law predicts +6 dB per octave.
Number of layers: Number of panel layers (1 = single leaf, 2+ = multi-leaf with air gap).
Air gap between layers (mm): Air space between layers in mm. Larger gap improves low-frequency isolation. 0 for single layer.

What each result means

Transmission loss (dB): Predicted sound transmission loss at the specified frequency, accounting for multi-layer effects.
Mass law TL (dB): Baseline transmission loss from mass law alone (20×log10(f×m) - 47).
Estimated STC (lab): Approximate Sound Transmission Class rating (laboratory conditions).
Estimated field STC: Expected field STC (typically 3-5 points lower than lab due to flanking).
Total surface mass (kg/m²): Combined surface mass of all layers.
Est. coincidence freq (Hz): Estimated critical/coincidence frequency where mass law dips (assuming gypsum-like material).

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Surface mass per layer (kg/m²) = 10, Frequency (Hz) = 500, Number of layers = 1, Air gap between layers (mm) = 0 = 4 input(s) provided
Calculate Transmission loss
26.7 = 26.7
Calculate Mass law TL
Mass law TL = 20 * log10(frequency * totalMass) - 47.3
26.7 = 26.7
Calculate Estimated STC
Estimated STC
27 = 27

Engine last updated July 28, 2026. Checked against 4 independently-derived tests — how we verify calculators.

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