Physics

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Thermal Resistance Calculator.

Calculate planar conduction resistance through a uniform layer.

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Set your values

Results update as you type.

Thermal resistance: 0.166667 K/W

Thermal resistance

0.000000K/W

Results update automatically as you type.

Use Cases

Insulation design

Evaluate the thermal resistance of insulation layers to ensure they meet building or industrial heat transfer requirements.

Example: Calculate resistance of 0.1 m foam with k=0.03 W/(m·K) over 10 m².

Heat sink analysis

Determine the conduction resistance of a heat sink base or thermal pad to optimize cooling performance.

Example: Check resistance of a 0.005 m aluminum layer (k=200) on a 0.01 m² chip.

Frequently Asked Questions

What is thermal resistance in conduction?
Thermal resistance is a measure of how much a material opposes heat flow. For planar conduction, it is calculated as the layer thickness divided by the product of thermal conductivity and conduction area. Lower resistance means easier heat flow.
How do I use the Thermal Resistance Calculator?
Enter the layer thickness in meters, thermal conductivity in W/(m·K), and conduction area in square meters. The calculator will compute the thermal resistance in K/W, which is the ratio of thickness to (conductivity × area).
What units are used in this calculator?
The calculator uses SI units: thickness in meters (m), thermal conductivity in watts per meter-kelvin (W/(m·K)), and area in square meters (m²). The result is thermal resistance in kelvin per watt (K/W).

Tips & Common Mistakes

Tips

  • Ensure all inputs are in the correct SI units: meters for thickness, W/(m·K) for conductivity, and square meters for area.
  • For composite layers, calculate each layer's resistance separately and add them for total resistance.
  • Use the calculator to compare materials: higher thermal conductivity reduces resistance for the same thickness and area.
  • Remember that this calculator assumes uniform material properties and steady-state conduction.

Common Mistakes to Avoid

  • Using thickness in centimeters or millimeters without converting to meters, leading to incorrect results.
  • Confusing thermal conductivity (W/(m·K)) with thermal resistance (K/W) – they are inversely related.
  • Forgetting to account for the conduction area; a larger area reduces resistance, not increases it.

Last updated: August 13, 2026