Heat Transfer Calculator (Conduction)
Find the steady state rate of heat flow through a flat material using Fourier's law of conduction, Q = k times A times deltaT divided by thickness. Useful for sizing insulation, walls and heat sinks.
How to calculate conductive heat transfer
- Enter the thermal conductivity k of the material in W/(m K).
- Enter the cross sectional area in square metres.
- Enter the temperature difference across the material in kelvin.
- Enter the material thickness in metres and read the heat transfer rate in watts.
Examples
Insulation panel
k = 0.04, A = 10 m2, deltaT = 20 K, d = 0.1 m
Q = 80 W
Thin steel plate
k = 50, A = 1 m2, deltaT = 100 K, d = 0.01 m
Q = 500000 W
Frequently asked questions
What is the conduction heat transfer formula?
Q = k * A * deltaT / d, where Q is the heat transfer rate in watts, k is thermal conductivity in W/(m K), A is the area in square metres, deltaT is the temperature difference in kelvin and d is the thickness in metres.
What units should I use?
SI units throughout: conductivity in W/(m K), area in square metres, temperature difference in kelvin and thickness in metres. The result is a heat transfer rate in watts (joules per second).
What are typical thermal conductivity values?
Roughly 0.03 to 0.05 W/(m K) for fibreglass or foam insulation, about 0.8 for glass, around 50 for steel, 205 for aluminium and 400 for copper.
Does thicker material reduce heat loss?
Yes. Thickness is in the denominator, so doubling the thickness halves the heat transfer rate for the same temperature difference. That is why thicker insulation saves energy.
Does this handle convection or radiation?
No. This calculator covers steady state conduction through a single solid layer only. Convection and radiation use different equations and are calculated separately.
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