Heat Transfer Calculator (Conduction)

Formula

• Q = k × A × ΔT / L
• R_th = L / (k × A)
• q″ = Q / A

About this calculator

Part of our Thermal & Fluids Calculators collection. Heat transfer, pipe flow, Reynolds number, and thermodynamic cycles.

How it works

Steady one-dimensional conduction through a plane wall uses Fourier's law. Heat rate Q equals k times area times temperature difference divided by thickness. Thermal resistance is thickness divided by k times area. Heat flux is Q divided by area.

Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.

Worked example

Steel plate k=50 W/m·K, A=0.01 m², ΔT=100 K, L=0.05 m.

1. Q = 50 × 0.01 × 100 / 0.05 = 1000 W
2. R_th = 0.05 / (50 × 0.01) = 0.1 K/W
3. q″ = 1000 / 0.01 = 100 kW/m²

Result: Heat rate 1000 W, flux 100 kW/m².

When to use

• Steady one-dimensional conduction through a plane wall
• Finding thermal resistance of insulation layers (single layer)
• Heat flux for furnace wall or heat sink estimates

Limitations

• Steady state, one-dimensional conduction only
• No convection or radiation at surfaces
• Uniform k and no internal heat generation

FAQ

What conductivity for steel?

Carbon steel ~45–50 W/m·K, stainless ~15 W/m·K, aluminium ~200 W/m·K.

How do I add convection?

Add surface convection resistances 1/(h×A) in series. This calculator covers conduction through the wall only.