Thermal Conductivity Calculator

Your details

Rearranges Fourier law to find any single unknown from the rest.
Choose a material to fill in its typical conductivity, or pick Custom and type your own.
Material property. Used unless you are solving for k, or a non-custom material is selected.
W/(m·K)
The face through which heat flows.
How far heat must travel across the material.
Hot-side minus cold-side. A kelvin difference equals the same Celsius difference.
K or °C
Currency
Heat-transfer rateModerate heat flow
80W
Heat-transfer rate (imperial)273Btu/hr
Heat flux (per m²)8W/m²
Thermal resistance (R)0.25K/W
R-value (per area, RSI)2.5m²·K/W
U-value0.4W/(m²·K)
80 W
Well insulated<50Moderate50-500High heat loss500+

Heat conducts through at 80 watts.

  • That is 80 joules of heat crossing the material every second, flowing from the hot side to the cold side.
  • The layer R-value (RSI) is 2.5 m²·K/W and its U-value is 0.4 W/(m²·K); a lower U-value means a better insulator.

Next stepTo cut heat loss, add a thicker layer, choose a lower-k material, or stack insulating layers in series to raise the total R-value.

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