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

February 8, 2024

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.

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:

q = –λT/Δx)

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

Table To Show The Thermal Conductivity Constants of Materials and Substances

Materials /SubstancesThermal Conductivity (W/mK)
Acetals0.23
Acetone0.16
Acetylene (gas)0.018
Acrylic0.2
Agate10.9
Air, atmosphere (gas)0.0262
Air, elevation 10000 m0.02
Alcohol0.17
Alumina36
Aluminum236
Aluminum Brass121
Aluminum Oxide30
Ammonia (gas)0.0249
Antimony18.5
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
Asphalt0.75
Balsa wood0.048
Beef, lean (78.9 % moisture)0.43 – 0.48
Benzene0.16
Beryllium201
Bismuth8.1
Bitumen0.17
Bitumen0.17
Bitumen/felt layers0.5
Blast furnace gas (gas)0.02
Boiler scale1.2 – 3.5
Boron25
Brass109
Breeze block0.10 – 0.20
Brick dense1.31
Brick, fire0.47
Brick, insulating0.15
Brickwork, common (Building Brick)0.6 -1.0
Brickwork, dense1.6
Bromine (gas)0.004
Bronze70
Brown iron ore0.58
Butter (15% moisture content)0.2
Cadmium96.6
Calcium silicate0.05
Carbon1.7
Carbon dioxide (gas)0.0146
Carbon monoxide0.0232
Carbon Steel45
Cast iron53
Cellulose acetate, molded, sheet0.17 – 0.33
Cellulose nitrate, celluloid0.12 – 0.21
Cellulose, cotton, wood pulp and regenerated0.23
Cement, mortar1.73
Cement, Portland0.29
Ceramic materials26-30
Chalk0.09
Charcoal0.084
Chlorinated poly-ether0.13
Chlorine (gas)0.0081
Chrom-oxide0.42
Chrome Nickel Steel16.3
Chromium94
Clay, dry to moist0.15 – 1.8
Clay, saturated0.6 – 2.5
Coal0.2
Cobalt69.21
Cod (83% moisture content)0.54
Coke0.184
Concrete, dense1.0 – 1.8
Concrete, lightweight0.1 – 0.3
Concrete, medium0.4 – 0.7
Concrete, stone1.7
Constantan23.3
Copper398
Corian (ceramic filled)1.06
Cork0.07
Cork board0.043
Cork, re-granulated0.044
Cotton0.04
Cotton wool0.029
Cotton Wool insulation0.029
Cupronickel 30%30
Diamond1000
Diatomaceous earth (Sil-o-cel)0.06
Diatomite0.12
Dichlorodifluoromethane R-12 (liquid)0.09
Dichlorodifluoromethane R-12 (gas)0.007
Duralium140
Earth, dry1.5
Ebonite0.17
Emery11.6
Engine Oil0.15
Epoxy0.35
Ethane (gas)0.018
Ether0.14
Ethylene (gas)0.017
Ethylene glycol0.25
Feathers0.034
Felt insulation0.04
Fiber hardboard0.2
Fiber insulating board0.048
Fiberglass0.04
Fire-clay brick 500 o C1.4
Fluorine (gas)0.0254
Foam glass0.045
Gasoline0.15
Glass1.05
Glass, Pearls, dry0.18
Glass, Pearls, saturated0.76
Glass, window0.96
Glass, wool Insulation0.04
Glycerol0.28
Gold318
Granite1.7 – 4.0
Graphite168
Gravel0.7
Ground or soil, dry area0.5
Ground or soil, moist area1
Ground or soil, very dry area0.33
Ground or soil, very moist area1.4
Gypsum board0.17
Hairfelt0.05
Hardboard high density0.15
Hardwoods (oak, maple..)0.16
Hastelloy C12
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
Inconel15
Ingot iron47 – 58
Insulation materials0.035 – 0.16
Iodine0.44
Iridium147
Iron73
Iron-oxide0.58
Kapok insulation0.034
Kerosene0.15
Krypton (gas)0.0088
Lead34
Leather, dry0.14
Limestone1.26 – 1.33
Lithium85
Magnesia insulation (85%)0.07
Magnesite4.15
Magnesium156
Magnesium alloy70 – 145
Marble2.08 – 2.94
Mercury, liquid28.9
Methane (gas)0.03
Methanol0.21
Mica0.71
Milk0.53
Mineral wool insulation materials, wool blankets ..0.04
Molybdenum142
Monel22
Neon (gas)0.046
Neoprene0.05
Nickel92
Nitric oxide (gas)0.0238
Nitrogen (gas)0.024
Nitrous oxide (gas)0.0151
Nylon 6, Nylon 6/60.25
Oil, machine lubricating SAE 500.15
Olive oil0.17
Oxygen (gas)0.024
Palladium70.9
Paper0.05
Paraffin Wax0.25
Peat0.08
Perlite, atmospheric pressure0.031
Perlite, vacuum0.00137
Phenol-formaldehyde moulding compounds0.13 – 0.25
Phenolic cast resins0.15
Phosphorbronze110
Pinchbeck159
Pit coal0.24
Pitch0.13
Plaster light0.2
Plaster, metal lath0.47
Plaster, sand0.71
Plaster, wood lath0.28
Plasticine0.65 – 0.8
Plastics, foamed (insulation materials)0.03
Platinum71.6
Plutonium6
Plywood0.13
Polycarbonate0.19
Polyester0.05
Polyethylene high density, PEH0.42 – 0.51
Polyethylene low density, PEL0.33
Polyisoprene hard rubber0.16
Polyisoprene natural rubber0.13
Polymethylmethacrylate0.17 – 0.25
Polypropylene, PP0.1 – 0.22
Polystyrene, expanded0.03
Polystyrol0.043
Polytetrafluoroethylene (PTFE)0.25
Polyurethane foam0.03
Polyvinylchloride, PVC0.19
Porcelain1.5
Potassium1
Potato, raw flesh0.55
Propane (gas)0.015
Pyrex glass1.005
Quartz mineral3
Radon (gas)0.0033
Red metal
Rhenium39.6
Rhodium151
Rock Wool insulation0.045
Rock, porous volcanic (Tuff)0.5 – 2.5
Rock, solid2 – 7
Rosin0.32
Rubber, cellular0.045
Rubber, natural0.13
Rubidium58
Salmon (73% moisture content)0.5
Sand, dry0.15 – 0.25
Sand, moist0.25 – 2
Sand, saturated2 – 4
Sandstone1.7
Sawdust0.08
Selenium0.52
Sheep wool0.039
Silica aerogel0.02
Silicon carbide120
Silicon cast resin0.15 – 0.32
Silicon oil0.1
Silver429
Slag wool0.042
Slate2.01
Snow (temp < 0 o C)0.05 – 0.25
Sodium140
Softwoods (fir, pine ..)0.12
Soil, clay1.1
Soil, saturated0.6 – 4
Soil, with organic matter0.15 – 2
Solder 50-5050
Soot0.07
Steam, low pressure0.0188
Steam, saturated0.0184
Steatite2
Steel, Carbon10-18
Steel, Stainless10-18
Straw slab insulation, compressed0.09
Styrofoam0.033
Sugars0.087 – 0.22
Sulfur dioxide (gas)0.0086
Sulfur, crystal0.2
Tantalum57
Tar0.19
Tellurium4.9
Thorium54
Timber, alder0.17
Timber, ash0.16
Timber, birch0.14
Timber, larch0.12
Timber, maple0.16
Timber, oak0.17
Timber, pitchpine0.14
Timber, pockwood0.19
Timber, red beech0.14
Timber, red pine0.15
Timber, walnut0.15
Timber, white pine0.15
Tin67
Titanium22
Tungsten170
Uranium27
Urethane foam0.021
Vacuum0
Vermiculite granules0.065
Vinyl ester0.25
Water0.606
Water, vapor (steam)28
Wheat flour0.45
White metal35 – 70
Wood across the grain, balsa0.055
Wood across the grain, white pine0.12
Wood across the grain, yellow pine, timber0.147
Wood wool, slab0.1 – 0.15
Wood, oak0.17
Wool, felt0.07
Xenon (gas)0.0051
Zinc120
Table 1: Table to show Thermal Conductivities (W/mK) of Materials and substances

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