Insulation Material Thermal Performance Calculator
Calculate R-value & U-value for insulation materials, with a reference table of common thermal conductivity values
Thermal Performance Calculator
Calculation Results
R-value (SI)
0.00 (m²·K)/W
R-value (Imperial)
0.00 (h·ft²·°F)/Btu
U-value (SI)
0.00 W/(m²·K)
U-value (Imperial)
0.00 Btu/(h·ft²·°F)
Calculation Principle & Formula
R = Thickness(m) / Thermal Conductivity(λ) = (Thickness(mm) ÷ 1000) ÷ λ
Where: Unit conversion – Convert millimeters (mm) to meters (m) by dividing by 1000.
U = 1 / R
R-value and U-value are reciprocals of each other.
SI Units
• R-value: (m²·K)/W
• U-value: W/(m²·K)
Imperial Units
• R-value: (h·ft²·°F)/Btu
• U-value: Btu/(h·ft²·°F)
Unit Conversion: 1 (m²·K)/W ≈ 5.678 (h·ft²·°F)/Btu
Common Insulation Materials — Thermal Conductivity
| Material Name | Density (kg/m³) | λ Range (W/(m·K)) | Typical λ (W/(m·K)) |
|---|---|---|---|
| Extruded Polystyrene (XPS) | 28-45 | 0.028-0.035 | 0.030 |
| Expanded Polystyrene (EPS) | 12-30 | 0.035-0.043 | 0.038 |
| Rock Wool Board | 40-200 | 0.035-0.046 | 0.040 |
| Glass Wool | 10-96 | 0.032-0.050 | 0.042 |
| Polyurethane Rigid Foam (PUR/PIR) | 30-55 | 0.019-0.025 | 0.022 |
| Phenolic Foam Board | 40-120 | 0.020-0.030 | 0.025 |
| Aerogel Blanket | 180-220 | 0.013-0.020 | 0.015 |
| Vacuum Insulated Panel (VIP) | 180-400 | 0.002-0.008 | 0.004 |
| Cork Board | 100-200 | 0.038-0.045 | 0.040 |
| Wood Fiber Board | 240-300 | 0.038-0.050 | 0.045 |
| Cellulose Fiber Fill | 45-60 | 0.038-0.042 | 0.040 |
| Polyisocyanurate Board (PIR) | 30-50 | 0.020-0.027 | 0.023 |
| Foam Glass | 120-180 | 0.038-0.050 | 0.045 |
| Expanded Perlite | 60-300 | 0.040-0.070 | 0.050 |
| Aluminum Silicate Wool | 96-128 | 0.035-0.045 | 0.040 |
About Thermal Conductivity
Thermal Conductivity (λ) measures how well a material conducts heat, in W/(m·K). The lower the value, the better the insulation performance.
Influencing Factors:
- Material type and structure
- Density (usually has an optimal range)
- Temperature (lower temperature typically reduces λ)
- Moisture (water content significantly increases λ)
For practical applications, refer to the product test report for the actual thermal conductivity value.