Heat Conduction Calculator

How to use the Heat Conduction Calculator

1. 1Enter the material, area, thickness and temperature difference.
2. 2Pick the units or options from the menus if the heat conduction tool offers them.
3. 3Read the heat conduction in the large result box.
4. 4Look at the extra rows for related figures.
5. 5Press Copy result to keep the answer.

When you need the heat conduction

Homeowners use it to compare insulation, and students use it in thermodynamics.

Doubling the thickness halves the heat flow. Insulation materials have a low k, so a thin layer helps a lot. The conductivity values listed are typical and vary by product.

How the heat conduction is worked out

Q = k × A × ΔT ÷ thickness, in watts, where k is the conductivity in W/m·K. R = thickness ÷ k and U = 1 ÷ R. A 230 mm brick wall (k about 0.7) of 10 m² with 20 °C between inside and outside loses 0.7 × 10 × 20 ÷ 0.23 = 609 W, which is about 14.6 kWh a day.

Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.

• Common materials built in
• R- and U-values
• Daily energy

Mistakes to avoid with heat conduction

Enter the thickness in millimetres, as the tool converts to metres. The calculation covers conduction only, not air films or radiation, so real losses in a building are somewhat different.

On phone and computer

On a phone, type into the boxes one after another and read the heat conduction underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the heat conduction move. The heat conduction calculator works the same on both.

Checking your heat conduction by hand

A good habit is to test the heat conduction calculator with a case you already know. A 230 mm brick wall (k about 0.7) of 10 m² with 20 °C between inside and outside loses 0.7 × 10 × 20 ÷ 0.23 = 609 W, which is about 14.6 kWh a day.

If your own figures give a surprising answer, repeat the working yourself: Q = k × A × ΔT ÷ thickness, in watts, where k is the conductivity in W/m·K. R = thickness ÷ k and U = 1 ÷ R. Small differences usually come from rounding, from mixing units, or from a typing slip in one of the inputs. Conduction is one of the ways heat moves, so compare it with others. Look at radiation with the Blackbody Radiation Calculator, expansion with the Thermal Expansion Calculator, and use the Temperature Converter when a source gives the wrong scale.

Features

• Thickness in mm
• Conduction only
• Typical k values vary
• Clear messages when the heat conduction inputs make no sense
• Copy the result with one tap
• Private: nothing is uploaded

Frequently asked questions