Material Insights · Understanding the Material World

Aluminium and Copper

Aluminium is the main substitute for copper in power cable, radiators, cooling tube and some electrical equipment, so the copper to aluminium price ratio, which rose from about 3.5 to about 4.1 times during 2025, shapes the incentive to switch; the two prices also share the industrial cycle.

Aluminium (commodity) and Copper (commodity): 4 relationships.

How they are linked

1. Substitute in cables and heat exchange

Substitution · Medium · Aluminium can replace copper, and copper can replace aluminium

Aluminium conducts electricity less well than copper but is far lighter and cheaper, so where space and joints allow it can do copper's job in power cable, electrical equipment, radiators and cooling tube.

  • about 61% aluminium's conductivity relative to copper, by volume
  • about 30% aluminium's weight relative to copper, by volume

Because it conducts less, an aluminium conductor must be thicker, typically two wire gauge sizes larger, to carry the same current, which suits overhead lines and large cables more than tight spaces. Joints are the weak point: connectors must be rated for aluminium, and high-resistance connections in older household aluminium wiring became a fire hazard, so copper keeps most building wire and electronics. USGS lists the swap in both directions: aluminium for copper in radiators, cooling and refrigeration tube, electrical equipment and power cable, and copper for aluminium in electrical and heat-exchange uses.

Sources: USGS; USGS; Wesco; AlCircle

2. Copper to aluminium price ratio

Cost and price · Medium · A wider ratio favours aluminium

Copper costs several times more than aluminium per tonne, so when the gap widens, cable makers and equipment designers gain more by switching to aluminium.

  • about 3.5 times LME copper to aluminium cash price, January 2025 (about $8,980 and $2,575 a tonne)
  • about 4.1 times same ratio at December 2025 levels (copper about $11,800 a tonne, aluminium near $2,875 at the year end)

Copper rose about 31% from its January average to its December level, against about 12% for aluminium, and USGS projected a record COMEX copper average of about $4.80 a pound for 2025, so the incentive to substitute grew over the year. Switching is slow because it needs product redesign, new standards and installer acceptance, so a high ratio works over years rather than months.

Sources: USGS; AlCircle

3. Price link: substitute

Cost and price · Strong · Both ways

Both metals are priced off the same industrial cycle of construction, power grids and vehicles, and substitution at the margin ties their prices further.

  • 0.67 monthly change correlation
  • 0.87 12-month change correlation
  • 1.01 fitted elasticity

Monthly price moves correlate at 0.67 and yearly moves at 0.87, so a sustained copper rally usually lifts aluminium too. The link can loosen when one metal has its own supply shock, such as power-driven smelter cuts for aluminium or mine disruptions for copper.

Sources: Material Insights (World Bank, FRED, IMF data)

4. Same Indian producer

Geography and ownership · High in India · Hindalco makes both metals

Hindalco produces both primary aluminium and refined copper at scale in India, so its plans shape domestic supply of both metals.

  • 1,323 kt Hindalco primary aluminium output, FY2024-25
  • 402 kt Hindalco copper cathode output, FY2024-25
  • 421 to 700 ktpa planned Dahej copper smelter expansion

The two businesses face different cost risks, power for aluminium and concentrate supply for copper, inside one company. India smelted about 4.2 Mt of primary aluminium in 2025 (USGS estimate), so Hindalco's output is roughly 30% of that base, though one figure is for a fiscal year and the other for a calendar year.

Sources: USGS; Hindalco Industries

For investors

Key learnings

  1. Aluminium limits how far copper users will pay up in cable and heat exchange uses, but substitution needs redesign and approvals, so it works over years, not months.
  2. The copper to aluminium price ratio widened from about 3.5 to about 4.1 times during 2025, strengthening the case for aluminium conductors.
  3. Prices share the industrial cycle, with yearly moves correlated at 0.87, so holding both is little diversification against a downturn.

What to track

  • LME copper to aluminium price ratio: A rising ratio increases the incentive to design copper out (Daily · LME)
  • LME copper and aluminium inventories: Falling copper stocks against ample aluminium widen the price ratio and the case to switch (Daily · LME)
  • Hindalco copper and aluminium output: Domestic supply of both metals in India (Quarterly · Hindalco results)

For policymakers

Key learnings

  1. Aluminium can relieve copper import needs in grid and cooling uses, provided standards and installer training cover aluminium joints.
  2. India produces both metals at scale, about 4.2 Mt of primary aluminium in 2025 and 402 kt of copper cathode at Hindalco alone in FY2024-25, so substitution can rest on domestic supply.
  3. Safety rules for connectors and terminations decide where aluminium can be used, so standards bodies hold a key lever.

What to track

  • Copper and aluminium import volumes: Shows how far domestic supply covers demand for each metal (Monthly · Ministry of Commerce trade data)
  • Standards for aluminium conductors and connectors: Wider approval allows more substitution in buildings and equipment (As revised · Bureau of Indian Standards)

India

India smelted about 4.2 Mt of primary aluminium in 2025, and Hindalco, which makes both metals, produced 1,323 kt of aluminium and 402 kt of copper cathode in FY2024-25 and plans to expand its Dahej copper smelter to 700 ktpa.

Sources

  1. Mineral Commodity Summaries 2026: Copper, USGS (2026)
  2. Mineral Commodity Summaries 2026: Aluminum, USGS (2026)
  3. Copper vs. aluminum conductors in industrial applications, Wesco
  4. LME throwback 2025: aluminium vs copper price and inventory movement, AlCircle (2026)
  5. Integrated Annual Report 2024-25: Report of the Board of Directors, Hindalco Industries (2025)
  6. Price correlation, Material Insights, Material Insights (World Bank, FRED, IMF data)