Soundproofing Calculator
Calculate wall STC rating and noise reduction for common drywall assemblies — compare soundproofing options and estimate material costs
Wall Assembly
Addons (toggle to add)
Room Dimensions
Estimated STC Rating
50
STC
NRC (Approx)
0.65
Noise Reduction
50
dB
Wall Area
468
ft²
Use Case Pass / Fail
Bedroom
STC 45+
PASS
Home Theater
STC 55+
—
Recording Studio
STC 65+
—
Material Cost Estimate
Drywall Sheets Needed
— sheets
MLV (sq ft)
— sq ft
Green Glue Tubes
— tubes
Est. Material Cost
$—
Common Wall Assembly Comparison
Compare six common wall assemblies by STC rating, approximate cost per square foot, and key trade-offs to help choose the right soundproofing approach for your project.
| Assembly | STC | Cost / ft² | Pros | Cons |
|---|---|---|---|---|
| Single drywall, 2×4 studs | 33 | $1.50–2.50 | Lowest cost, standard construction | Minimal noise isolation, most common failure |
| Double drywall, 2×4 studs | 38 | $2.50–3.50 | Simple upgrade, adds mass | Still flanks through studs, limited improvement |
| Single drywall + resilient channel | 44 | $3.00–4.50 | Decouples drywall, breaks vibration path | RC shorts if screws touch studs — requires care |
| Double drywall + resilient channel | 50 | $4.50–6.50 | Excellent mass + decoupling combo | Thicker wall, higher cost |
| Staggered stud wall | 52 | $5.00–7.00 | No rigid connections, good low-freq control | Wider footprint (6–8"), more framing material |
| Double stud with air gap | 60 | $8.00–14.00 | Best isolation, pro-grade studio standard | Expensive, loses 10–14" of room width |
All STC values are for assemblies filled with acoustic insulation (R-11 or R-13 mineral wool). Add +3 for mass loaded vinyl and +6 for Green Glue damping compound between drywall layers.
STC Rating Guide by Use Case
| STC Range | What You Hear | Typical Use Case |
|---|---|---|
| 25–30 | Normal speech clearly audible | Interior partition (no sound control) |
| 30–35 | Loud speech audible, normal speech faint | Basic apartment separation |
| 40–45 | Loud speech heard as murmur | Bedroom, office, hotel room |
| 50–55 | Very loud sounds faintly audible | Home theater, music room |
| 60–65 | Most sounds inaudible | Recording studio, drum room |
| 65+ | Virtually no transmission | Professional studio, critical listening |
Common Sound Flanking Paths & Fixes
- Electrical outlets & switches — Back-to-back outlets create a direct path. Offset boxes by at least one stud bay; use putty pads to seal.
- Windows & doors — Even STC 50 walls fail with a hollow-core door (STC 20). Upgrade to solid-core door and add door sweeps and acoustic seals.
- Gaps & penetrations — Acoustic caulk around all perimeter edges, pipe penetrations, and conduit entries. Sound travels through gaps smaller than 1mm.
- HVAC ducts — Sheet metal ducts transmit sound between rooms. Use flexible duct connectors and lined duct wrap; consider duct silencers for critical rooms.
- Structure-borne noise — Impact noise from floors travels through joists. Floating floor systems and resilient clips on ceiling joists address this separately from STC.
- Resilient channel short-circuits — If drywall screws penetrate through RC into studs, decoupling is lost. Use 1" type-S screws and keep screw length in check.
Product Recommendations
| Product Type | Common Brand | STC Contribution | Approx. Cost |
|---|---|---|---|
| Mass Loaded Vinyl (1 lb/ft²) | TMS, Acoustimac | +3 STC | $1.00–1.75/ft² |
| Green Glue Compound | Green Glue | +5–6 STC | $15–18/tube (covers 16 ft²) |
| Resilient Channel (RC-1) | Various | +8–12 STC | $0.60–0.90/ft |
| Acoustic Mineral Wool | Rockwool Safe'n'Sound | +4–6 STC | $0.80–1.20/ft² |
| Type X 5/8" Drywall | USG, National Gypsum | Base mass | $0.55–0.80/ft² |
| Sound-dampening drywall | QuietRock 530 | +10–15 STC vs standard | $3.50–4.50/ft² |