Thermal Conductivity & Fourier Heat Conduction Calculator

Thermodynamics, Fourier Heat Conduction & Thermal Conductivity Metrology

Thermal conductivity (k or λ) is the material property governing the rate of conductive heat transfer:

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• Universal Thermal Conductivity Conversion Formulas (ASTM Standards)**:

k_BTU/(h·ft·^) = k_W/(m·K)1.730735 = k_W/(m·K) × 0.577789

k_BTU·in/(h·ft^2·^) = k_W/(m·K)0.144228 = k_W/(m·K) × 6.93347

1 cal/(s·cm·^) = 418.4 W/(m·K)

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• Fourier's Law of Thermal Conduction & Insulation R-Value**:

Q = (k × A × Δ T) / (L) (Watts, W)

R-Value per Inch = (1) / (k_BTU)·in/(h·ft^2·^)

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• Standard Material Thermal Conductivity Benchmarks**:

• Synthetic Diamond: 2,200.0 W/(m·K) 1,271.1 BTU/(h·ft·^) (Phonon conduction)

• Pure Copper: 400.0 W/(m·K) 231.12 BTU/(h·ft·^) (Free electron gas)

• Aluminum 6061: 167.0 W/(m·K) 96.49 BTU/(h·ft·^)

• Stainless Steel 304: 15.0 W/(m·K) 8.67 BTU/(h·ft·^)

• Liquid Water (20°C): 0.60 W/(m·K) 0.347 BTU/(h·ft·^)

• Fiberglass Insulation: 0.040 W/(m·K) k=0.277 R-3.61 per inch

How to Use This Calculator

Enter your Thermal Conductivity Magnitude (k / λ) (e.g. 400 in k), From Thermal Conductivity Unit — choose from Watts per Meter-Kelvin (W/(m·K) - SI Base Unit), BTU per Hour-Foot-Fahrenheit (BTU/(h·ft·°F) - Imperial Engineering), BTU-Inch per Hour-SqFt-°F (k-factor - ASTM Insulation Standard), To Thermal Conductivity Unit — choose from Watts per Meter-Kelvin (W/(m·K)), BTU per Hour-Foot-Fahrenheit (BTU/(h·ft·°F)), BTU-Inch per Hour-SqFt-°F (k-factor), Cross-Sectional Conduction Area (A in m²) (e.g. 0.01 in m²), Material Thickness / Conduction Path (L in meters) (e.g. 0.05 in m), Temperature Difference Across Material (ΔT in °C) (e.g. 50 in Δ°C), and Material Conduction Benchmark — choose from Custom Thermal Conductivity, Pure Copper (400.0 W/(m·K)) → 231.12 BTU/(h·ft·°F) | Q̇ = 4,000 W (0.01m² @ 50°C/0.05m), Aluminum 6061 (167.0 W/(m·K)) → 96.49 BTU/(h·ft·°F) | Q̇ = 1,670 W. Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Fourier's Law Conduction Rate: Q_dot = (k A Delta_T) / L (in Watts)

Worked Example

An electronic thermal engineer evaluating a pure copper heat sink base, area 0.01 m^2, thickness 50 mm) facing a 50^ temperature drop calculates it conducts exactly 4,000 Watts of heat.

Understanding Your Result

Unit conversions are exact by definition within a given measurement system (e.g., 1 km = exactly 1,000 m). Cross-system conversions (metric to imperial) use defined exchange factors: 1 inch = exactly 2.54 cm; 1 pound = 0.45359237 kg. Round your converted result to match the precision of your original measurement — expressing more decimal places than your input justifies implies false accuracy. For regulatory, legal, or safety-critical applications, verify which measurement system is required by the applicable standard.