The Ultimate Guide to Thermal Conductivity | Calculator, Definitions, and Application

Hassan Ahmed — Tue, 20 May 2025 22:53:45 +0000

The Thermal Conductivity Calculator is designed to compute the thermal conductivity of materials or determine the heat flux through objects based on Fourier’s law. This guide offers a clear explanation of thermal conductivity, demonstrates how to apply the heat flux formula accurately, and discusses the units of thermal conductivity in detail.

What Is Thermal Conductivity?

Thermal Conductivity is defined as how well a material can conduct heat, a characteristic intrinsic to the material itself, unaffected by external factors or the mass of the object. This property is directly related to the amount of heat energy conveyed and the distance over which this heat is transferred, while being inversely related to the difference in temperature throughout the material.

The most common example looked at within educational institutions is a wall with insulation. So consider a wall with insulation. If it only allows a minimal amount of heat to pass through, its thermal conductivity is considered to be low.

We recommend the following book for an introduction into thermodynamics:

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Fourier’s Law Definition

Fourier’s Law, states that the rate at which heat is transferred through a material is proportional to the negative gradient of the temperature and the area through which the heat is being transferred. In simpler terms, it means that heat moves from regions of higher temperature to regions of lower temperature, and the amount of heat transferred per unit of time is directly related to how quickly the temperature changes in space (temperature gradient) and the size of the area over which the heat transfer occurs.

Heat Flux Definiton

Heat flux refers to the amount of heat energy that moves through a specific area every second. It is used within Fourier’s Law and is usually combined as seen below.

Heat Flux and Fourier’s Law

According to Fourier’s law, heat flux is defined as:

Where:

q – Heat Flux, measured in (W/m²)
Δx – Thickness of the object (or the distance the heat has to travel) in (m)
ΔT – The temperature difference across the object in (K)
λ – The Thermal Conductivity of the material (W/mK)

The negative sign expresses the direction of heat transfer. Due to heat always flowing from a warm area to a cold area, the direction of heat transfer is always opposite to the temperature gradient.

Thermal Conductivity Calculator

Thermal Conductivity (k):

Temperature Difference (ΔT):

Distance (Δx):

Heat Flux = –

Table To Show The Thermal Conductivity Constants of Materials and Substances

Materials /Substances	Thermal Conductivity (W/mK)
Acetals	0.23
Acetone	0.16
Acetylene (gas)	0.018
Acrylic	0.2
Agate	10.9
Air, atmosphere (gas)	0.0262
Air, elevation 10000 m	0.02
Alcohol	0.17
Alumina	36
Aluminum	236
Aluminum Brass	121
Aluminum Oxide	30
Ammonia (gas)	0.0249
Antimony	18.5
Apple (85.6% moisture)	0.39
Argon (gas)	0.016
Asbestos mill board 1)	0.14
Asbestos, loosely packed 1)	0.15
Asbestos-cement 1)	2.07
Asbestos-cement board 1)	0.744
Asbestos-cement sheets 1)	0.166
Asphalt	0.75
Balsa wood	0.048
Beef, lean (78.9 % moisture)	0.43 – 0.48
Benzene	0.16
Beryllium	201
Bismuth	8.1
Bitumen	0.17
Bitumen	0.17
Bitumen/felt layers	0.5
Blast furnace gas (gas)	0.02
Boiler scale	1.2 – 3.5
Boron	25
Brass	109
Breeze block	0.10 – 0.20
Brick dense	1.31
Brick, fire	0.47
Brick, insulating	0.15
Brickwork, common (Building Brick)	0.6 -1.0
Brickwork, dense	1.6
Bromine (gas)	0.004
Bronze	70
Brown iron ore	0.58
Butter (15% moisture content)	0.2
Cadmium	96.6
Calcium silicate	0.05
Carbon	1.7
Carbon dioxide (gas)	0.0146
Carbon monoxide	0.0232
Carbon Steel	45
Cast iron	53
Cellulose acetate, molded, sheet	0.17 – 0.33
Cellulose nitrate, celluloid	0.12 – 0.21
Cellulose, cotton, wood pulp and regenerated	0.23
Cement, mortar	1.73
Cement, Portland	0.29
Ceramic materials	26-30
Chalk	0.09
Charcoal	0.084
Chlorinated poly-ether	0.13
Chlorine (gas)	0.0081
Chrom-oxide	0.42
Chrome Nickel Steel	16.3
Chromium	94
Clay, dry to moist	0.15 – 1.8
Clay, saturated	0.6 – 2.5
Coal	0.2
Cobalt	69.21
Cod (83% moisture content)	0.54
Coke	0.184
Concrete, dense	1.0 – 1.8
Concrete, lightweight	0.1 – 0.3
Concrete, medium	0.4 – 0.7
Concrete, stone	1.7
Constantan	23.3
Copper	398
Corian (ceramic filled)	1.06
Cork	0.07
Cork board	0.043
Cork, re-granulated	0.044
Cotton	0.04
Cotton wool	0.029
Cotton Wool insulation	0.029
Cupronickel 30%	30
Diamond	1000
Diatomaceous earth (Sil-o-cel)	0.06
Diatomite	0.12
Dichlorodifluoromethane R-12 (liquid)	0.09
Dichlorodifluoromethane R-12 (gas)	0.007
Duralium	140
Earth, dry	1.5
Ebonite	0.17
Emery	11.6
Engine Oil	0.15
Epoxy	0.35
Ethane (gas)	0.018
Ether	0.14
Ethylene (gas)	0.017
Ethylene glycol	0.25
Feathers	0.034
Felt insulation	0.04
Fiber hardboard	0.2
Fiber insulating board	0.048
Fiberglass	0.04
Fire-clay brick 500 o C	1.4
Fluorine (gas)	0.0254
Foam glass	0.045
Gasoline	0.15
Glass	1.05
Glass, Pearls, dry	0.18
Glass, Pearls, saturated	0.76
Glass, window	0.96
Glass, wool Insulation	0.04
Glycerol	0.28
Gold	318
Granite	1.7 – 4.0
Graphite	168
Gravel	0.7
Ground or soil, dry area	0.5
Ground or soil, moist area	1
Ground or soil, very dry area	0.33
Ground or soil, very moist area	1.4
Gypsum board	0.17
Hairfelt	0.05
Hardboard high density	0.15
Hardwoods (oak, maple..)	0.16
Hastelloy C	12
Helium (gas)	0.142
Honey (12.6% moisture content)	0.5
Hydrochloric acid (gas)	0.013
Hydrogen (gas)	0.168
Hydrogen sulfide (gas)	0.013
Ice (0 o C, 32 o F)	2.18
Inconel	15
Ingot iron	47 – 58
Insulation materials	0.035 – 0.16
Iodine	0.44
Iridium	147
Iron	73
Iron-oxide	0.58
Kapok insulation	0.034
Kerosene	0.15
Krypton (gas)	0.0088
Lead	34
Leather, dry	0.14
Limestone	1.26 – 1.33
Lithium	85
Magnesia insulation (85%)	0.07
Magnesite	4.15
Magnesium	156
Magnesium alloy	70 – 145
Marble	2.08 – 2.94
Mercury, liquid	28.9
Methane (gas)	0.03
Methanol	0.21
Mica	0.71
Milk	0.53
Mineral wool insulation materials, wool blankets ..	0.04
Molybdenum	142
Monel	22
Neon (gas)	0.046
Neoprene	0.05
Nickel	92
Nitric oxide (gas)	0.0238
Nitrogen (gas)	0.024
Nitrous oxide (gas)	0.0151
Nylon 6, Nylon 6/6	0.25
Oil, machine lubricating SAE 50	0.15
Olive oil	0.17
Oxygen (gas)	0.024
Palladium	70.9
Paper	0.05
Paraffin Wax	0.25
Peat	0.08
Perlite, atmospheric pressure	0.031
Perlite, vacuum	0.00137
Phenol-formaldehyde moulding compounds	0.13 – 0.25
Phenolic cast resins	0.15
Phosphorbronze	110
Pinchbeck	159
Pit coal	0.24
Pitch	0.13
Plaster light	0.2
Plaster, metal lath	0.47
Plaster, sand	0.71
Plaster, wood lath	0.28
Plasticine	0.65 – 0.8
Plastics, foamed (insulation materials)	0.03
Platinum	71.6
Plutonium	6
Plywood	0.13
Polycarbonate	0.19
Polyester	0.05
Polyethylene high density, PEH	0.42 – 0.51
Polyethylene low density, PEL	0.33
Polyisoprene hard rubber	0.16
Polyisoprene natural rubber	0.13
Polymethylmethacrylate	0.17 – 0.25
Polypropylene, PP	0.1 – 0.22
Polystyrene, expanded	0.03
Polystyrol	0.043
Polytetrafluoroethylene (PTFE)	0.25
Polyurethane foam	0.03
Polyvinylchloride, PVC	0.19
Porcelain	1.5
Potassium	1
Potato, raw flesh	0.55
Propane (gas)	0.015
Pyrex glass	1.005
Quartz mineral	3
Radon (gas)	0.0033
Red metal
Rhenium	39.6
Rhodium	151
Rock Wool insulation	0.045
Rock, porous volcanic (Tuff)	0.5 – 2.5
Rock, solid	2 – 7
Rosin	0.32
Rubber, cellular	0.045
Rubber, natural	0.13
Rubidium	58
Salmon (73% moisture content)	0.5
Sand, dry	0.15 – 0.25
Sand, moist	0.25 – 2
Sand, saturated	2 – 4
Sandstone	1.7
Sawdust	0.08
Selenium	0.52
Sheep wool	0.039
Silica aerogel	0.02
Silicon carbide	120
Silicon cast resin	0.15 – 0.32
Silicon oil	0.1
Silver	429
Slag wool	0.042
Slate	2.01
Snow (temp < 0 o C)	0.05 – 0.25
Sodium	140
Softwoods (fir, pine ..)	0.12
Soil, clay	1.1
Soil, saturated	0.6 – 4
Soil, with organic matter	0.15 – 2
Solder 50-50	50
Soot	0.07
Steam, low pressure	0.0188
Steam, saturated	0.0184
Steatite	2
Steel, Carbon	10-18
Steel, Stainless	10-18
Straw slab insulation, compressed	0.09
Styrofoam	0.033
Sugars	0.087 – 0.22
Sulfur dioxide (gas)	0.0086
Sulfur, crystal	0.2
Tantalum	57
Tar	0.19
Tellurium	4.9
Thorium	54
Timber, alder	0.17
Timber, ash	0.16
Timber, birch	0.14
Timber, larch	0.12
Timber, maple	0.16
Timber, oak	0.17
Timber, pitchpine	0.14
Timber, pockwood	0.19
Timber, red beech	0.14
Timber, red pine	0.15
Timber, walnut	0.15
Timber, white pine	0.15
Tin	67
Titanium	22
Tungsten	170
Uranium	27
Urethane foam	0.021
Vacuum	0
Vermiculite granules	0.065
Vinyl ester	0.25
Water	0.606
Water, vapor (steam)	28
Wheat flour	0.45
White metal	35 – 70
Wood across the grain, balsa	0.055
Wood across the grain, white pine	0.12
Wood across the grain, yellow pine, timber	0.147
Wood wool, slab	0.1 – 0.15
Wood, oak	0.17
Wool, felt	0.07
Xenon (gas)	0.0051
Zinc	120

Hassan Ahmed

Hassan graduated with a Master’s degree in Chemical Engineering from the University of Chester (UK). He currently works as a design engineering consultant for one of the largest engineering firms in the world along with being an associate member of the Institute of Chemical Engineers (IChemE).

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