What is the thermal conductivity of copper?

About 401 W/m·K at room temperature — the highest of the common engineering metals after silver. This is why copper is used for heatsinks, heat exchangers and bus bars.

What is the thermal conductivity of stainless steel?

About 16 W/m·K for 304 and 316 at room temperature — roughly 25 times lower than copper, and about a quarter of that of plain carbon steel. This low conductivity is what makes stainless useful as an insulator in cryogenic equipment, and difficult to weld and machine.

What is the thermal conductivity of aluminium?

About 237 W/m·K for pure aluminium. Alloying reduces it — 6061 is about 167 and 7075 about 130 — but it remains far better than steel, which is why aluminium heatsinks are common even though copper performs better per unit volume.

Which metal conducts heat best?

Silver, at about 429 W/m·K, followed by copper at 401 and gold at 317. Silver is rarely used because of cost; copper gives most of the performance at a fraction of the price.

Does thermal conductivity change with temperature?

Yes. For metals it generally falls as temperature rises, because lattice vibrations scatter the conducting electrons more. For gases it rises with temperature. The values here are at room temperature.

What is the difference between thermal conductivity and thermal conductance?

Conductivity (k) is a property of the material alone. Conductance (U or h) also includes the thickness and area of a specific part — it is conductivity divided by thickness. A thin sheet of a poor conductor can have higher conductance than a thick slab of a better one.

Thermal Conductivity Chart

Thermal conductivity for metals, polymers, fluids and gases — in W/m·K and imperial units, from silver at 429 down to air at 0.026.

Data verified 2026-09-29 · based on n/a — physical property data, no governing revision

Quick Answer

Thermal conductivity is the rate heat moves through a material, in W/m·K. Metals span a huge range: copper at 401 conducts about 25 times better than stainless steel and roughly 1,600 times better than PEEK. That ratio is why copper is used for heatsinks and stainless for insulation in cryogenic service.

Find a material

Thermal Conductivity of Common Materials

Material^[2]	Conductivity W/m·K^[2]	Conductivity BTU·in/h·ft²·°F^[1]	Class^[2]
Silver #	429	2971	Metal
Copper #	401	2777	Metal
Gold #	317	2196	Metal
Aluminium #	237	1642	Metal
Brass (70/30) #	110	762	Metal
Nickel #	90	623	Metal
Iron, pure #	80	554	Metal
Steel, carbon 1% #	43	298	Metal
Lead #	35	242	Metal
Titanium #	22	152	Metal
Stainless 316 #	16.3	113	Metal
Stainless 304 #	16.2	112	Metal
Inconel 718 #	11.4	79	Metal
Glass, window #	1.05	7.3	Non-metal
Concrete #	1.7	11.8	Non-metal
Brick, common #	0.6	4.2	Non-metal
Water (20 °C) #	0.6	4.2	Fluid
Engine oil #	0.145	1.0	Fluid
PVC #	0.19	1.3	Polymer
PTFE #	0.25	1.7	Polymer
PEEK #	0.25	1.7	Polymer
Delrin (POM) #	0.31	2.1	Polymer
Wood, oak #	0.17	1.2	Non-metal
Air (20 °C) #	0.026	0.18	Gas

Values are at approximately 20–25 °C. Thermal conductivity is temperature-dependent, and for alloys it also depends on composition and heat treatment — a specific grade's value should come from its own data sheet where precision matters.

The Unit and Why It Matters

Thermal conductivity k is the heat flow through a unit thickness for a unit temperature difference: W/m·K in metric, BTU·in/h·ft²·°F in imperial. The imperial unit contains inches rather than feet because conduction calculations usually involve a wall or sheet of known thickness in inches.

The two are not a simple ratio because of the inch in the imperial unit — the conversion factor is 6.933, not 5.678 (which is the factor for BTU·ft/h·ft²·°F).

What the Range Tells You

The spread is enormous — four orders of magnitude from silver to air.

Pure metals conduct best, and the best conductors are also the best electrical conductors. This is not a coincidence: in metals, free electrons carry both heat and charge.
Alloying sharply reduces conductivity. Pure copper is 401; adding zinc to make brass drops it to about 110, and adding chromium and nickel to make stainless drops it to 16. The alloying elements scatter the electrons that were doing the conducting.
Polymers and gases are insulators, which is why foams work: the polymer structure is weak enough, but the trapped gas is what actually stops the heat.

A practical consequence for machining: stainless steel, titanium and nickel alloys conduct heat away from the cutting edge poorly, so the heat stays in the tool. That is a large part of why they are difficult to machine.

Frequently Asked Questions

What is the thermal conductivity of copper?: About 401 W/m·K at room temperature — the highest of the common engineering metals after silver. This is why copper is used for heatsinks, heat exchangers and bus bars.
What is the thermal conductivity of stainless steel?: About 16 W/m·K for 304 and 316 at room temperature — roughly 25 times lower than copper, and about a quarter of that of plain carbon steel. This low conductivity is what makes stainless useful as an insulator in cryogenic equipment, and difficult to weld and machine.
What is the thermal conductivity of aluminium?: About 237 W/m·K for pure aluminium. Alloying reduces it — 6061 is about 167 and 7075 about 130 — but it remains far better than steel, which is why aluminium heatsinks are common even though copper performs better per unit volume.
Which metal conducts heat best?: Silver, at about 429 W/m·K, followed by copper at 401 and gold at 317. Silver is rarely used because of cost; copper gives most of the performance at a fraction of the price.
Does thermal conductivity change with temperature?: Yes. For metals it generally falls as temperature rises, because lattice vibrations scatter the conducting electrons more. For gases it rises with temperature. The values here are at room temperature.
What is the difference between thermal conductivity and thermal conductance?: Conductivity (k) is a property of the material alone. Conductance (U or h) also includes the thickness and area of a specific part — it is conductivity divided by thickness. A thin sheet of a poor conductor can have higher conductance than a thick slab of a better one.

Value Sources

Each data column on this page is tied to the source it came from. The numbers in square brackets correspond to the table headers above.

#	Source	Type	Revision / method
[1]	Imperial conversion	derived	W/m·K × 6.933 = BTU·in/h·ft²·°F (the inch-based form of the imperial unit).
[2]	Standard engineering handbook values (ASM Metals Reference Book and comparable sources)	standard	n/a — compiled physical property data, not a revisioned specification — source

Data Sources

Standard	Revision	What it covers on this page
Compiled engineering handbook values	n/a — physical property data, no governing revision	thermal conductivity values for all materials listed

Cross-checked against:

Values cross-checked against two independent handbook sources
Imperial column recomputed from the metric column at build time

Derived values — the following values on this page are calculated, not taken directly from the standard:

Value	How it is derived
Imperial conductivity column	W/m·K × 6.933.

Values are typical room-temperature figures. Conductivity varies with temperature, and for alloys with composition and condition — use the specific grade data sheet where precision matters.

Accuracy and use. The values on this page are compiled from the published standards and cross-checked sources listed above. Where values are derived, the derivation is stated. No warranty, express or implied, is made as to the accuracy or completeness of this information, and no liability is accepted for any loss or damage arising from its use. Engineering reference data is provided for guidance in preliminary work — before a value is used for design, fabrication or acceptance testing, verify it against the current revision of the governing standard and against your own inspection. The user assumes all risk and responsibility in connection with the use of this information.

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Every value on this page is traceable to the sources listed above. If you use the data in a document, paper or report, cite it as:

Plain text

Engineering Reference. "Thermal Conductivity Chart." https://refmanual.com/charts/thermal-conductivity/ (accessed 2026-09-29). Data from Compiled engineering handbook values, n/a — physical property data, no governing revision.

BibTeX

@misc{thermal-conductivity,
  title        = {Thermal Conductivity Chart},
  author       = {{Engineering Reference}},
  howpublished = {\url{https://refmanual.com/charts/thermal-conductivity/}},
  note         = {Accessed: 2026-09-29},
  source       = {Compiled engineering handbook values, n/a — physical property data, no governing revision}
}

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TY  - ELEC
TI  - Thermal Conductivity Chart
AU  - Engineering Reference
PB  - Engineering Reference
UR  - https://refmanual.com/charts/thermal-conductivity/
PY  - 2026
DA  - 2026-09-29
N1  - Source: Compiled engineering handbook values, n/a — physical property data, no governing revision
ER  -

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