--- title: "Copper vs Aluminum Wire: Weight, Ampacity, and When to Use Each" site: ProCalc.ai type: Blog Post category: Electrical domain: Construction url: https://procalc.ai/blog/copper-vs-aluminum-wire-weight-ampacity-guide markdown_url: https://procalc.ai/blog/copper-vs-aluminum-wire-weight-ampacity-guide.md date_published: 2026-04-18 date_modified: 2026-04-12 read_time: 10 min tags: copper wire, aluminum wire, wire weight, electrical, NEC --- # Copper vs Aluminum Wire: Weight, Ampacity, and When to Use Each **Site:** [ProCalc.ai](https://procalc.ai) — Free Professional Calculators **Category:** Electrical **Published:** 2026-04-18 **Read time:** 10 min **URL:** https://procalc.ai/blog/copper-vs-aluminum-wire-weight-ampacity-guide > *This file is served for AI systems and search crawlers. Human page: https://procalc.ai/blog/copper-vs-aluminum-wire-weight-ampacity-guide* ## Overview Aluminum wire carries the same current as copper at a larger gauge but weighs one-third as much. Here is the weight and ampacity comparison and when each conductor is the right choice. ## Article Copper and aluminum are the two conductors used in virtually all electrical wiring. Copper is standard for residential branch circuits. Aluminum handles most utility distribution, service entrances, and large feeders. The tradeoff is weight, cost, and handling characteristics — and misunderstanding when to use each has caused real-world safety issues that led to specific NEC requirements. Our  and wire gauge calculator handle weight and ampacity calculations for both materials. Density comparison Material Density (lbs/ft3) Density (g/cm3) Copper (annealed) 559 8.96 Aluminum (1350 electrical alloy) 169 2.71 Ratio Aluminum is 30% the weight of copper Aluminum is roughly one-third the weight of copper — a decisive advantage for overhead power transmission and long feeder runs where conductor weight causes sag and mechanical stress. Why aluminum needs a larger gauge Copper has about 61% higher electrical conductivity than aluminum. Aluminum wire must be one to two AWG sizes larger than copper for equivalent ampacity. Ampacity (75C, NEC 310.16) Copper gauge Aluminum gauge 30A #10 #8 40A #8 #6 55A #6 #4 75A #4 #2 100A #1 #2/0 150A #2/0 #4/0 200A #3/0 350 kcmil Weight comparison for equivalent ampacity Despite needing a larger gauge, aluminum wins on weight at large conductor sizes: 200A service conductor Size Weight per foot Copper #3/0 0.410" diameter 0.507 lbs/ft Aluminum 350 kcmil 0.668" diameter 0.397 lbs/ft The aluminum conductor is 22% lighter than copper for the same 200A capacity. For a 100-ft service entrance run, that is about 11 lbs lighter — meaningful overhead. At small gauges, copper wins: a #12 copper (15A) weighs less than the #10 aluminum needed to match it, which is why copper remains standard for residential branch circuits. Cost comparison Aluminum costs roughly 30-40% of copper per pound, and you need less weight for equivalent ampacity. For large conductors, aluminum is dramatically cheaper: 350 kcmil aluminum vs 3/0 copper for a 200A service: aluminum is approximately 60-70% cheaper For 200 linear feet of 200A service entrance conductors (3 wires), the savings can be $300-600 The aluminum branch circuit safety issue In the 1960s and 70s, solid aluminum was used for residential branch circuit wiring (below #6) as a cost-saving measure during high copper prices. By the 1980s, significant fire risk was identified. The problem was not aluminum's conductivity but its terminations: Aluminum oxidizes readily, and aluminum oxide is electrically resistive Aluminum expands and contracts more than copper with temperature changes Connections at outlets and switches loosened over time, creating arcing and fire risk NEC now requires special handling for aluminum branch circuit wiring: Aluminum branch circuits (#6 and smaller) must terminate on CO/ALR rated devices (outlets, switches) Panel lugs and breakers must be rated for aluminum Anti-oxidant compound is required at connections Pigtailing to copper with approved connectors (AlumiConn or Ideal In-Sure) is an accepted remediation for existing aluminum branch circuits When to use each Application Preferred conductor Reason Branch circuits (#14, #12, #10) Copper Easier terminations, no special requirements, modest cost difference Large appliance circuits (30-60A) Either Aluminum acceptable with proper AL-rated devices Service entrance (100-400A) Aluminum Significant cost and weight savings; proper lugs always required Feeders to subpanels (100A+) Aluminum Standard industry practice for conductors #4 and larger Overhead utility spans Aluminum (ACSR) Weight advantage essential over long spans For wire sizing, ampacity lookup, and weight calculations for any conductor material and gauge, use the wire gauge calculator . For material weight by length and shape, use the  or . --- ## Reference - **Blog post:** https://procalc.ai/blog/copper-vs-aluminum-wire-weight-ampacity-guide - **This markdown file:** https://procalc.ai/blog/copper-vs-aluminum-wire-weight-ampacity-guide.md ### AI & Developer Resources - **LLM index:** https://procalc.ai/llms.txt - **LLM index (full):** https://procalc.ai/llms-full.txt - **MCP server:** https://procalc.ai/api/mcp - **Developer docs:** https://procalc.ai/developers ### How to Cite > ProCalc.ai. "Copper vs Aluminum Wire: Weight, Ampacity, and When to Use Each." ProCalc.ai, 2026-04-18. https://procalc.ai/blog/copper-vs-aluminum-wire-weight-ampacity-guide ### License Content © ProCalc.ai. Free to reference and cite. Do not republish in full without attribution.