---
title: "Does it conduct electricity? Ranked against copper"
description: "Which materials conduct and how well, as a percentage of copper — plus the ones that surprise people, like diamond, graphite and carbon fibre."
url: https://atoneplace.net/does-it-conduct/
site: "At One Place"
---

# Does it conduct electricity?

55 materials with whether they conduct and, for the 36 that do, how well — as a percentage of copper, which is the standard the industry actually uses.

## Ranked against copper

*IACS — the International Annealed Copper Standard. Silver, at about 105 %, is the only element above copper.*

| Material | % of copper | Note |
| --- | --- | --- |
| silver | 105% | The best electrical conductor of any element, better than copper — and too expensive to use for anything but contacts and high-frequency plating. |
| copper | 100% | The reference standard. Every other conductivity figure is quoted as a percentage of copper. |
| gold | 70% | Slightly worse than copper, but it does not tarnish — which is why contacts and connectors are gold plated rather than made of it. |
| aluminum | 61% | About 61 % of copper by volume but far better by weight, which is why overhead power lines are aluminium: thicker cable, much lighter towers. |
| aluminum 6061 | 43% | Lower than pure aluminium, because alloying always costs conductivity. |
| magnesium | 39% | Reasonable, but the metal is used for lightness rather than conduction. |
| aluminum 7075 | 33% | Lower again. |
| tungsten | 31% | Moderate, and it is used for its melting point rather than its conductivity. |
| brass | 28% | Moderate. Good enough for electrical fittings where machinability matters more than conductivity. |
| zinc | 27% | Adequate, rarely used for conduction. |
| nickel | 24% | Modest for a metal. |
| iron | 17% | A poor conductor for a metal, about a sixth as good as copper, which is why it is a structural material rather than a wiring one. |
| platinum | 16% | Poor for a precious metal, used for its chemical stability instead. |
| tin | 15% | Poor, and mostly relevant as a solder constituent. |
| bronze | 15% | Modest. |
| chromium | 13% | Poor. Chrome plating is for appearance and hardness, not conduction. |
| wrought iron | 12% | Poor. |
| tin-lead solder (60/40) | 12% | Much poorer than the copper it joins, which is why a solder joint is a mechanical and sealing device rather than the conducting path. |
| lead-free solder (SAC305) | 11% | Similar to leaded solder and for the same reason unimportant. |
| mild steel | 10% | Poor, around a tenth of copper. |
| pewter | 10% | Poor. |
| high-carbon steel | 9% | Poor. |
| lead | 8% | A poor conductor, and heavy, so used for shielding rather than wiring. |
| tool steel | 7% | Poor. |
| tungsten carbide | 5% | Conducts, which is what makes it usable as an electrode material. |
| gray cast iron | 4% | Poor electrically, and also a mediocre thermal conductor — cast iron pans are prized for heat capacity rather than conductivity. |
| ductile iron | 4% | Poor. |
| Monel 400 | 3.5% | Poor. |
| titanium | 3% | A remarkably poor conductor for a metal, about a thirtieth of copper. |
| stainless steel 304 | 2.5% | Very poor, about 2.5 % of copper — worse than plain steel, because the alloying elements scatter electrons. |
| stainless steel 316 | 2.3% | Very poor, marginally worse than 304. |
| mercury | 2% | A very poor conductor, and the only metal that is liquid at room temperature — which is what old tilt switches used it for. |
| Inconel 718 | 1.4% | Very poor. |
| Ti-6Al-4V titanium alloy | 1% | About one per cent of copper — among the poorest conductors of any structural metal. |
| unidirectional carbon fibre composite | 1% | Conductive along the fibres, which surprises people who assume a composite is plastic. It is why carbon fibre laptop shells need care around electronics and why lightning strike protection is a real design problem on composite aircraft. |
| graphite | 0.1% | The exception among non-metals: graphite conducts because each carbon atom has a spare electron delocalised across the sheet. Diamond, the same element bonded differently, is an insulator. |

## The ones that surprise people

- Silver conducts better than copper. It is not used for wiring because it costs a hundred times more and tarnishes.
- Aluminium is only 61 % as conductive as copper by volume and far better by weight, which is why every overhead transmission line is aluminium and no house is wired in it.
- Diamond is an insulator and the best thermal conductor known — five times better than copper at moving heat while moving no current at all.
- Graphite is the same element and conducts electricity well, because its layers leave one electron per atom free.
- Carbon fibre conducts, which makes lightning protection a real design problem on composite aircraft.
- Stainless steel is a very poor conductor, around 2.5 % of copper — worse than plain steel, because the alloying elements scatter electrons.

## Everything

| Material | Verdict | Note |
| --- | --- | --- |
| mild steel | Conducts electricity | Poor, around a tenth of copper. |
| aluminum | Conducts electricity | About 61 % of copper by volume but far better by weight, which is why overhead power lines are aluminium: thicker cable, much lighter towers. |
| water | Does not conduct | Pure water is an insulator. Tap water conducts because of dissolved ions, not because of the water — which is why the electrical hazard from water is really a hazard from what is in it. |
| copper | Conducts electricity | The reference standard. Every other conductivity figure is quoted as a percentage of copper. |
| gold | Conducts electricity | Slightly worse than copper, but it does not tarnish — which is why contacts and connectors are gold plated rather than made of it. |
| titanium | Conducts electricity | A remarkably poor conductor for a metal, about a thirtieth of copper. |
| concrete | Does not conduct | Insulating when dry, semi-conducting when wet, which is why concrete floors are treated as conductive for electrical safety. |
| stainless steel 304 | Conducts electricity | Very poor, about 2.5 % of copper — worse than plain steel, because the alloying elements scatter electrons. |
| iron | Conducts electricity | A poor conductor for a metal, about a sixth as good as copper, which is why it is a structural material rather than a wiring one. |
| air | Does not conduct | An excellent insulator until it is not: at roughly 3 kV per millimetre it ionises and becomes a conductor, which is what a spark and a lightning strike are. |
| ice | Does not conduct | A poorer conductor than liquid water, because the ions cannot move through the lattice. |
| lead | Conducts electricity | A poor conductor, and heavy, so used for shielding rather than wiring. |
| tungsten | Conducts electricity | Moderate, and it is used for its melting point rather than its conductivity. |
| brass | Conducts electricity | Moderate. Good enough for electrical fittings where machinability matters more than conductivity. |
| pine | Does not conduct | Dry wood is an insulator. Wet wood is not, and it is the moisture that conducts — which is why electricians do not treat a wooden ladder as safe. |
| silver | Conducts electricity | The best electrical conductor of any element, better than copper — and too expensive to use for anything but contacts and high-frequency plating. |
| gray cast iron | Conducts electricity | Poor electrically, and also a mediocre thermal conductor — cast iron pans are prized for heat capacity rather than conductivity. |
| diamond | Does not conduct | An electrical insulator and simultaneously the best thermal conductor known — around five times better than copper at conducting heat while conducting no electricity at all. Structure, not composition, decides both. |
| high-carbon steel | Conducts electricity | Poor. |
| stainless steel 316 | Conducts electricity | Very poor, marginally worse than 304. |
| granite | Does not conduct | An insulator when dry. |
| aluminum 6061 | Conducts electricity | Lower than pure aluminium, because alloying always costs conductivity. |
| soda-lime glass | Does not conduct | An excellent insulator at room temperature, and a conductor when molten — which is how glass is electrically melted industrially. |
| PTFE | Does not conduct | Among the best insulators available, which is why it is the dielectric in high-frequency coaxial cable. |
| marble | Does not conduct | An insulator. |
| unidirectional carbon fibre composite | Conducts electricity | Conductive along the fibres, which surprises people who assume a composite is plastic. It is why carbon fibre laptop shells need care around electronics and why lightning strike protection is a real design problem on composite aircraft. |
| rigid PVC | Does not conduct | A good insulator, and the commonest cable sheathing material in the world. |
| fibreglass (GRP) | Does not conduct | An insulator — the reason electricians' ladders and hot-stick tools are fibreglass and not aluminium. |
| bronze | Conducts electricity | Modest. |
| natural rubber | Does not conduct | A good insulator, and historically the first one used for cable. |
| paper | Does not conduct | An insulator when dry, and used as one — oil-impregnated paper insulated high-voltage cable for most of the twentieth century. |
| mercury | Conducts electricity | A very poor conductor, and the only metal that is liquid at room temperature — which is what old tilt switches used it for. |
| aluminum 7075 | Conducts electricity | Lower again. |
| tungsten carbide | Conducts electricity | Conducts, which is what makes it usable as an electrode material. |
| silicone rubber | Does not conduct | An insulator, and it retains that property at temperatures where most polymers have failed. |
| zinc | Conducts electricity | Adequate, rarely used for conduction. |
| magnesium | Conducts electricity | Reasonable, but the metal is used for lightness rather than conduction. |
| tool steel | Conducts electricity | Poor. |
| graphite | Conducts electricity | The exception among non-metals: graphite conducts because each carbon atom has a spare electron delocalised across the sheet. Diamond, the same element bonded differently, is an insulator. |
| reinforced concrete | Does not conduct | The concrete insulates; the reinforcement forms a continuous conductive cage, which is why buildings can use it for earthing. |
| red oak | Does not conduct | Insulating when dry. |
| tin-lead solder (60/40) | Conducts electricity | Much poorer than the copper it joins, which is why a solder joint is a mechanical and sealing device rather than the conducting path. |
| platinum | Conducts electricity | Poor for a precious metal, used for its chemical stability instead. |
| tin | Conducts electricity | Poor, and mostly relevant as a solder constituent. |
| Ti-6Al-4V titanium alloy | Conducts electricity | About one per cent of copper — among the poorest conductors of any structural metal. |
| nickel | Conducts electricity | Modest for a metal. |
| lead-free solder (SAC305) | Conducts electricity | Similar to leaded solder and for the same reason unimportant. |
| chromium | Conducts electricity | Poor. Chrome plating is for appearance and hardness, not conduction. |
| silicon carbide | Conducts, but only under some conditions | A wide-bandgap semiconductor, which is why it is displacing silicon in electric-vehicle power electronics and fast chargers. |
| leather | Does not conduct | Insulating when dry. |
| wrought iron | Conducts electricity | Poor. |
| ductile iron | Conducts electricity | Poor. |
| Inconel 718 | Conducts electricity | Very poor. |
| pewter | Conducts electricity | Poor. |
| Monel 400 | Conducts electricity | Poor. |

- [Does mild steel conduct?](https://atoneplace.net/does-it-conduct/mild-steel/) — Conducts electricity
- [Does aluminum conduct?](https://atoneplace.net/does-it-conduct/aluminum/) — Conducts electricity
- [Does water conduct?](https://atoneplace.net/does-it-conduct/water/) — Does not conduct
- [Does copper conduct?](https://atoneplace.net/does-it-conduct/copper/) — Conducts electricity
- [Does gold conduct?](https://atoneplace.net/does-it-conduct/gold/) — Conducts electricity
- [Does titanium conduct?](https://atoneplace.net/does-it-conduct/titanium/) — Conducts electricity
- [Does concrete conduct?](https://atoneplace.net/does-it-conduct/concrete/) — Does not conduct
- [Does stainless steel 304 conduct?](https://atoneplace.net/does-it-conduct/stainless-304/) — Conducts electricity
- [Does iron conduct?](https://atoneplace.net/does-it-conduct/iron/) — Conducts electricity
- [Does air conduct?](https://atoneplace.net/does-it-conduct/air/) — Does not conduct
- [Does ice conduct?](https://atoneplace.net/does-it-conduct/ice/) — Does not conduct
- [Does lead conduct?](https://atoneplace.net/does-it-conduct/lead/) — Conducts electricity
- [Does tungsten conduct?](https://atoneplace.net/does-it-conduct/tungsten/) — Conducts electricity
- [Does brass conduct?](https://atoneplace.net/does-it-conduct/brass/) — Conducts electricity
- [Does pine conduct?](https://atoneplace.net/does-it-conduct/pine/) — Does not conduct
- [Does silver conduct?](https://atoneplace.net/does-it-conduct/silver/) — Conducts electricity
- [Does gray cast iron conduct?](https://atoneplace.net/does-it-conduct/cast-iron/) — Conducts electricity
- [Does diamond conduct?](https://atoneplace.net/does-it-conduct/diamond/) — Does not conduct
- [Does high-carbon steel conduct?](https://atoneplace.net/does-it-conduct/carbon-steel/) — Conducts electricity
- [Does stainless steel 316 conduct?](https://atoneplace.net/does-it-conduct/stainless-316/) — Conducts electricity
- [Does granite conduct?](https://atoneplace.net/does-it-conduct/granite/) — Does not conduct
- [Does aluminum 6061 conduct?](https://atoneplace.net/does-it-conduct/aluminum-6061/) — Conducts electricity
- [Does soda-lime glass conduct?](https://atoneplace.net/does-it-conduct/soda-lime-glass/) — Does not conduct
- [Does ptfe conduct?](https://atoneplace.net/does-it-conduct/ptfe/) — Does not conduct
- [Does marble conduct?](https://atoneplace.net/does-it-conduct/marble/) — Does not conduct
- [Does unidirectional carbon fibre composite conduct?](https://atoneplace.net/does-it-conduct/carbon-fiber-ud/) — Conducts electricity
- [Does rigid pvc conduct?](https://atoneplace.net/does-it-conduct/pvc-rigid/) — Does not conduct
- [Does fibreglass (grp) conduct?](https://atoneplace.net/does-it-conduct/fiberglass/) — Does not conduct
- [Does bronze conduct?](https://atoneplace.net/does-it-conduct/bronze/) — Conducts electricity
- [Does natural rubber conduct?](https://atoneplace.net/does-it-conduct/natural-rubber/) — Does not conduct
- [Does paper conduct?](https://atoneplace.net/does-it-conduct/paper/) — Does not conduct
- [Does mercury conduct?](https://atoneplace.net/does-it-conduct/mercury/) — Conducts electricity
- [Does aluminum 7075 conduct?](https://atoneplace.net/does-it-conduct/aluminum-7075/) — Conducts electricity
- [Does tungsten carbide conduct?](https://atoneplace.net/does-it-conduct/tungsten-carbide/) — Conducts electricity
- [Does silicone rubber conduct?](https://atoneplace.net/does-it-conduct/silicone-rubber/) — Does not conduct
- [Does zinc conduct?](https://atoneplace.net/does-it-conduct/zinc/) — Conducts electricity
- [Does magnesium conduct?](https://atoneplace.net/does-it-conduct/magnesium/) — Conducts electricity
- [Does tool steel conduct?](https://atoneplace.net/does-it-conduct/tool-steel/) — Conducts electricity
- [Does graphite conduct?](https://atoneplace.net/does-it-conduct/graphite/) — Conducts electricity
- [Does reinforced concrete conduct?](https://atoneplace.net/does-it-conduct/reinforced-concrete/) — Does not conduct
- [Does red oak conduct?](https://atoneplace.net/does-it-conduct/red-oak/) — Does not conduct
- [Does tin-lead solder (60/40) conduct?](https://atoneplace.net/does-it-conduct/solder-60-40/) — Conducts electricity
- [Does platinum conduct?](https://atoneplace.net/does-it-conduct/platinum/) — Conducts electricity
- [Does tin conduct?](https://atoneplace.net/does-it-conduct/tin/) — Conducts electricity
- [Does ti-6al-4v titanium alloy conduct?](https://atoneplace.net/does-it-conduct/ti-6al-4v/) — Conducts electricity
- [Does nickel conduct?](https://atoneplace.net/does-it-conduct/nickel/) — Conducts electricity
- [Does lead-free solder (sac305) conduct?](https://atoneplace.net/does-it-conduct/solder-lead-free/) — Conducts electricity
- [Does chromium conduct?](https://atoneplace.net/does-it-conduct/chromium/) — Conducts electricity
- [Does silicon carbide conduct?](https://atoneplace.net/does-it-conduct/silicon-carbide/) — Conducts, but only under some conditions
- [Does leather conduct?](https://atoneplace.net/does-it-conduct/leather/) — Does not conduct
- [Does wrought iron conduct?](https://atoneplace.net/does-it-conduct/wrought-iron/) — Conducts electricity
- [Does ductile iron conduct?](https://atoneplace.net/does-it-conduct/ductile-iron/) — Conducts electricity
- [Does inconel 718 conduct?](https://atoneplace.net/does-it-conduct/inconel-718/) — Conducts electricity
- [Does pewter conduct?](https://atoneplace.net/does-it-conduct/pewter/) — Conducts electricity
- [Does monel 400 conduct?](https://atoneplace.net/does-it-conduct/monel-400/) — Conducts electricity

## Common questions

### What is the best electrical conductor?

Silver, at about 105 % of copper on the IACS scale. Copper is used instead because silver costs roughly a hundred times more and tarnishes.

### Why are power lines aluminium and not copper?

Aluminium is 61 % as conductive by volume but far better by weight. A thicker aluminium conductor carries the same current for much less mass, so the towers can be lighter and further apart — which dominates the cost of a transmission line.

### Does pure water conduct electricity?

No. Pure water is an insulator; tap water conducts because of dissolved ions. The electrical hazard from water comes from what is dissolved in it.