Wondering how well your walls can block sound? Use our STC Rating Calculator to instantly estimate the Sound Transmission Class (STC) rating of your wall construction.
What Is STC and Why Does It Matter?
STC (Sound Transmission Class) is the industry standard for measuring how well a wall, floor, or ceiling assembly reduces airborne sound transfer. The higher the STC, the better the sound blocking.
This tool is designed to help:
- Homeowners planning quiet bedrooms or nurseries
- Contractors evaluating compliance with building codes
- Studio builders, podcasters, and musicians targeting high-STC spaces
- Architects designing sound-rated walls in multifamily or commercial buildings
How This Calculator Works
Simply select your wall assembly components:
- Wall structure: 2×4, 2×6, concrete, CMU, brick, steel stud, double wall
- Drywall layers: Single or double ½” or ⅝” drywall, plaster
- Insulation type and density
- Soundproofing add-ons: Mass loaded vinyl (MLV), resilient channels, Green Glue
- Sealing level: With or without acoustic sealant
You’ll get:
- An estimated STC rating (range: STC 25–65+)
- A breakdown of how each material contributes to the rating
- A color-coded performance label (Poor, Fair, Good, Very Good, Excellent)
- Building code compliance feedback
- Suggestions to increase STC with affiliate product links
[Calculate Your Wall’s STC Rating]
STC Performance Scale
| STC Rating | Sound Blocking | Real-World Example |
|---|---|---|
| 25–35 | Poor | Normal conversation heard clearly |
| 36–42 | Fair | Loud speech heard, but slightly muffled |
| 43–50 | Good | Raised voices heard but not intelligible |
| 51–60 | Very Good | Loud music barely audible |
| 61+ | Excellent | Most airborne noise blocked |
Example Assemblies and STC Values
| Wall Assembly | Estimated STC |
|---|---|
| 2×4 studs + single ½” drywall each side | STC 34 |
| 2×6 studs + single ⅝” drywall each side | STC 37 |
| Double 2×4 stud walls, air gap + insulation | STC 50+ |
| 8″ CMU block wall | STC 45 |
| Brick wall (4″) | STC 40 |
Improve Your Wall’s STC with Add-Ons
| Upgrade Type | STC Gain (Approx.) |
|---|---|
| Fiberglass insulation | +2 to +5 |
| Rockwool/mineral wool | +3 to +6 |
| 1/4″ MLV | +5 to +8 |
| Resilient channels | +3 to +8 |
| Clips + hat channel | +5 to +12 |
| Green Glue between drywall | +6 to +10 |
| Acoustic sealing | +1 to +3 |
The calculator automatically adjusts for diminishing returns and component interaction, giving you a realistic estimate based on laboratory testing data.
Building Code Compliance Guide
| Project Type | Minimum STC Required |
|---|---|
| Residential shared walls | STC 50+ |
| Commercial office spaces | STC 55+ |
| Hotels and multifamily | STC 50–55 |
Your result will indicate if your assembly meets or does not meet code based on your input. A compliance summary will offer explanations and tips to help you reach the required rating.
Recommendations for STC Improvement
After seeing your result, we’ll suggest:
- Next best upgrades ranked by STC improvement per dollar
- Most cost-effective materials to reach your target
- Complete soundproofing kits for quick installation
Recommended Products (Available on Amazon)
- Mass Loaded Vinyl (MLV)
- Rockwool Insulation
- Resilient Clips and Hat Channels
- Green Glue Damping Compound
- Acoustic Caulk
Understand the Limits of STC
- STC only measures airborne sound, not impact noise or vibration
- STC does not fully account for low-frequency sounds like bass or machinery
- Real-world STC is often 3–5 points lower than lab-tested ratings due to installation quality and flanking paths
For critical applications like music studios, theaters, or courtrooms, we recommend consulting with an acoustic engineer or investing in professional field testing.
Need to Compare Multiple Wall Designs?
Use our Comparison Mode to save multiple assemblies and compare side-by-side to find the best-performing solution within your budget.
STC Rating Calculator Key Features
- Live STC updates as you select components
- Mobile-optimized for on-site contractors and designers
- Clear visual rating gauge and performance bars
- Assembly diagram and material breakdown
- Print or export your results to PDF
- Direct links to trusted product sources
Let me know if you’d like a matching:
- Meta title & meta description
- Featured image for the tool
- FAQ section below the calculator
- Internal linking strategy to other tools on your site (like the Acoustic Panel Calculator or Soundproofing Cost Estimator)
