The American Wire Gauge (AWG) system rates wire from 40 AWG (thinnest, 0.003 inches) to 4/0 AWG (thickest common residential, 0.460 inches), with smaller numbers indicating thicker wire and higher ampacity. For residential wiring, 14 AWG carries up to 15 amps, 12 AWG handles 20 amps, 10 AWG supports 30 amps, and the scale continues up to 4/0 AWG at 195–230 amps depending on insulation temperature rating.
Below you'll find the most comprehensive AWG wire gauge charts available — covering copper and aluminum conductors across all three NEC temperature columns, physical dimensions, resistance values, and practical application guidance for every gauge you'll encounter in residential and light commercial work.
Master AWG Wire Gauge Chart — Copper Conductors
This is the complete reference table based on NEC Table 310.16 for copper conductors rated 0–2000 volts. These ampacity values apply to no more than 3 current-carrying conductors in a raceway or cable at an ambient temperature of 30°C (86°F).
| AWG | Diameter (in) | Area (kcmil) | 60°C (TW, UF) | 75°C (THW, THWN, XHHW) | 90°C (THHN, THWN-2, XHHW-2) | Typical Residential Use |
|---|---|---|---|---|---|---|
| 18 | 0.0403 | 1.62 | — | — | 14A | Thermostat wire, bell wire |
| 16 | 0.0508 | 2.58 | — | — | 18A | Low-voltage control circuits |
| 14 | 0.0641 | 4.11 | 15A | 20A | 25A | 15A lighting circuits |
| 12 | 0.0808 | 6.53 | 20A | 25A | 30A | 20A outlet circuits |
| 10 | 0.1019 | 10.38 | 30A | 35A | 40A | AC units, water heaters, dryers |
| 8 | 0.1285 | 16.51 | 40A | 50A | 55A | Ranges, large AC, sub-panels |
| 6 | 0.1620 | 26.24 | 55A | 65A | 75A | Sub-panels, large loads, EV chargers |
| 4 | 0.2043 | 41.74 | 70A | 85A | 95A | Feeders, sub-panels |
| 3 | 0.2294 | 52.62 | 85A | 100A | 115A | 100A sub-panels |
| 2 | 0.2576 | 66.36 | 95A | 115A | 130A | Large feeders |
| 1 | 0.2893 | 83.69 | 110A | 130A | 145A | Service entrance |
| 1/0 | 0.3249 | 105.6 | 125A | 150A | 170A | 150A service |
| 2/0 | 0.3648 | 133.1 | 145A | 175A | 195A | 200A service |
| 3/0 | 0.4096 | 167.8 | 165A | 200A | 225A | 200A service (long run) |
| 4/0 | 0.4600 | 211.6 | 195A | 230A | 260A | 200A+ service |
NEC 240.4(D) overrides these ampacity values for small branch circuits. Regardless of insulation temperature rating, 14 AWG is capped at 15A, 12 AWG at 20A, and 10 AWG at 30A for branch circuit overcurrent protection. The higher ampacity values for 75°C and 90°C insulation apply only for derating calculations, not for breaker sizing.
AWG Wire Gauge Chart — Aluminum Conductors
Aluminum conductors have approximately 61% the conductivity of copper, requiring larger gauges for equivalent ampacity. Modern AA-8000 series aluminum alloy (required by NEC 310.14 since 1972) is the standard for residential service entrance and feeder applications.
| AWG | Diameter (in) | Area (kcmil) | 60°C (TW, UF) | 75°C (THW, THWN, XHHW) | 90°C (THHN, THWN-2, XHHW-2) | Typical Use |
|---|---|---|---|---|---|---|
| 12 | 0.0808 | 6.53 | 15A | 20A | 25A | Rarely used residential |
| 10 | 0.1019 | 10.38 | 25A | 30A | 35A | Rarely used residential |
| 8 | 0.1285 | 16.51 | 30A | 40A | 45A | Small feeders |
| 6 | 0.1620 | 26.24 | 40A | 50A | 60A | Sub-panel feeders |
| 4 | 0.2043 | 41.74 | 55A | 65A | 75A | Sub-panel feeders |
| 3 | 0.2294 | 52.62 | 65A | 75A | 85A | Feeders |
| 2 | 0.2576 | 66.36 | 75A | 90A | 100A | 100A service |
| 1 | 0.2893 | 83.69 | 85A | 100A | 115A | Service entrance |
| 1/0 | 0.3249 | 105.6 | 100A | 120A | 135A | 100–125A service |
| 2/0 | 0.3648 | 133.1 | 115A | 135A | 150A | 150A service |
| 3/0 | 0.4096 | 167.8 | 130A | 155A | 175A | 175A service |
| 4/0 | 0.4600 | 211.6 | 150A | 180A | 205A | 200A service |
| 250 | — | 250.0 | 170A | 205A | 230A | 200A service (long run) |
| 300 | — | 300.0 | 190A | 230A | 255A | 225A service |
| 350 | — | 350.0 | 210A | 250A | 280A | 250A service |
Quick copper-to-aluminum conversion: To get equivalent ampacity in aluminum, go up approximately 2 AWG sizes. For example, 6 AWG copper (55A at 60°C) is roughly equivalent to 4 AWG aluminum (55A at 60°C). This rule works well for sizes 4 AWG through 4/0 AWG.
Wire Resistance Chart
Wire resistance determines voltage drop over distance. This is critical for long runs to HVAC equipment, detached garages, and outbuildings.
| AWG | Copper (Ω/1000 ft) | Aluminum (Ω/1000 ft) | Copper (Ω/km) | Aluminum (Ω/km) |
|---|---|---|---|---|
| 14 | 3.14 | 5.17 | 10.30 | 16.96 |
| 12 | 1.98 | 3.25 | 6.50 | 10.66 |
| 10 | 1.24 | 2.04 | 4.07 | 6.69 |
| 8 | 0.778 | 1.28 | 2.55 | 4.20 |
| 6 | 0.491 | 0.808 | 1.61 | 2.65 |
| 4 | 0.308 | 0.508 | 1.01 | 1.67 |
| 3 | 0.245 | 0.403 | 0.80 | 1.32 |
| 2 | 0.194 | 0.319 | 0.64 | 1.05 |
| 1 | 0.154 | 0.253 | 0.51 | 0.83 |
| 1/0 | 0.122 | 0.201 | 0.40 | 0.66 |
| 2/0 | 0.0967 | 0.159 | 0.32 | 0.52 |
| 3/0 | 0.0766 | 0.126 | 0.25 | 0.41 |
| 4/0 | 0.0608 | 0.100 | 0.20 | 0.33 |
Wire Weight and Cost Comparison
Understanding cost helps you make practical decisions, especially for long runs where material costs add up.
| AWG | Copper Weight (lb/1000 ft) | Aluminum Weight (lb/1000 ft) | Copper NM-B Cost ($/ft, 2026 est.) | Aluminum SE Cost ($/ft, 2026 est.) |
|---|---|---|---|---|
| 14/2 NM-B | 26.0 | — | $0.25–$0.40 | — |
| 12/2 NM-B | 37.8 | — | $0.35–$0.55 | — |
| 10/2 NM-B | 55.0 | — | $0.65–$1.00 | — |
| 10/3 NM-B | 73.0 | — | $0.85–$1.30 | — |
| 8/2 NM-B | 84.0 | — | $1.20–$1.80 | — |
| 8/3 NM-B | 112.0 | — | $1.60–$2.40 | — |
| 6/3 NM-B | 168.0 | — | $2.50–$3.80 | — |
| 6 THHN | 31.4 | 9.6 | $0.60–$0.90/conductor | $0.25–$0.40/conductor |
| 4 THHN | 49.9 | 15.3 | $0.95–$1.40/conductor | $0.40–$0.60/conductor |
| 2/0 SE | — | 53.8 | — | $1.50–$2.50/cable |
| 4/0 SE | — | 85.5 | — | $2.50–$4.00/cable |
Copper prices fluctuate significantly. The prices above are estimates for early 2026. Copper commodity prices directly affect wire costs. In 2022–2024, copper surged above $4.50/lb, pushing 10/2 NM-B above $1.00/ft at retail. Check current pricing before budgeting large projects.
Understanding Temperature Ratings
The three temperature columns in NEC Table 310.16 correspond to the insulation type on the wire. This matters more than most people realize.
60°C Column (TW, UF-B, NM-B)
This is the most conservative rating and what you use for standard Romex (NM-B) branch circuits. Even though NM-B cable actually contains 90°C-rated conductors, the cable assembly is rated at 60°C. For branch circuit breaker sizing under NEC 240.4(D), this column doesn't even matter — the breaker cap is more restrictive.
75°C Column (THW, THWN, XHHW, USE)
Used for individual conductors in conduit with 75°C insulation. This is common for HVAC equipment connections in conduit, service entrance wiring, and feeder circuits. Most terminal connections on equipment (breakers, disconnects, outlets) are rated for 75°C conductors.
90°C Column (THHN, THWN-2, XHHW-2)
The highest standard rating. You can use this column's ampacity for derating calculations (adjusting for ambient temperature or conduit fill), but the actual overcurrent protection must be based on the 75°C or 60°C column matching your termination temperature rating.
Practical example: You're running 6 AWG THHN (90°C rated) through conduit with 4 current-carrying conductors. The 90°C ampacity is 75A, and the derating factor for 4 conductors is 80%. So: 75A × 0.80 = 60A. Since 60A is still above the 75°C column value of 65A — wait, it's below. So you'd use 60A as your effective ampacity. The breaker cannot exceed 60A.
Ampacity Derating Factors
When multiple conductors share a raceway or cable, or when ambient temperature exceeds 30°C, you must derate the ampacity values.
Conduit Fill Derating (NEC 310.15(C)(1))
| Number of Current-Carrying Conductors | Adjustment Factor |
|---|---|
| 1–3 | 100% (no derating) |
| 4–6 | 80% |
| 7–9 | 70% |
| 10–20 | 50% |
| 21–30 | 45% |
| 31–40 | 40% |
| 41+ | 35% |
Ambient Temperature Correction (NEC Table 310.15(B)(1))
| Ambient Temp (°C) | Ambient Temp (°F) | 60°C Wire Factor | 75°C Wire Factor | 90°C Wire Factor |
|---|---|---|---|---|
| 21–25 | 70–77 | 1.08 | 1.05 | 1.04 |
| 26–30 | 79–86 | 1.00 | 1.00 | 1.00 |
| 31–35 | 88–95 | 0.91 | 0.94 | 0.96 |
| 36–40 | 97–104 | 0.82 | 0.88 | 0.91 |
| 41–45 | 106–113 | 0.71 | 0.82 | 0.87 |
| 46–50 | 115–122 | 0.58 | 0.75 | 0.82 |
| 51–55 | 124–131 | 0.41 | 0.67 | 0.76 |
Attic runs in hot climates: If you're running NM-B cable through an attic in Arizona or Texas where summer temperatures hit 60°C (140°F), the derating is severe. A 12 AWG copper conductor rated 20A at 30°C drops to just 11.6A at 60°C ambient with 60°C insulation. This is why HVAC wiring in hot attics often requires upsizing.
Wire Sizing by Application
Common Residential Circuits
| Application | Circuit | Wire Gauge | Breaker | Cable Type | Notes |
|---|---|---|---|---|---|
| Bedroom lighting | 120V, 15A | 14 AWG | 15A SP | 14/2 NM-B | AFCI required |
| Kitchen outlets | 120V, 20A | 12 AWG | 20A SP | 12/2 NM-B | GFCI + AFCI, 2 circuits min |
| Bathroom outlets | 120V, 20A | 12 AWG | 20A SP | 12/2 NM-B | GFCI required |
| Garage outlets | 120V, 20A | 12 AWG | 20A SP | 12/2 NM-B | GFCI required |
| Outdoor outlets | 120V, 20A | 12 AWG | 20A SP | 12/2 UF-B | GFCI required, wet-rated cable |
| Dishwasher | 120V, 20A | 12 AWG | 20A SP | 12/2 NM-B | Dedicated circuit |
| Garbage disposal | 120V, 20A | 12 AWG | 20A SP | 12/2 NM-B | Dedicated circuit |
HVAC Circuits
| Equipment | Circuit | Wire Gauge | Breaker | Cable Type | Notes |
|---|---|---|---|---|---|
| Central AC (2-3 ton) | 240V | 10 AWG | 30A DP | 10/2 NM-B | Check nameplate MCA/MOP |
| Central AC (4-5 ton) | 240V | 8-6 AWG | 40-50A DP | THHN in conduit | Check nameplate MCA/MOP |
| Heat pump | 240V | 10-6 AWG | 30-50A DP | Varies | Plus strip heat circuit |
| Gas furnace | 120V | 14 AWG | 15A SP | 14/2 NM-B | Low amperage (5-12A) |
| Electric furnace | 240V | 6-3 AWG | 60-100A DP | THHN in conduit | High draw, dedicated panel |
| Mini-split (9-12k) | 120/240V | 14-12 AWG | 15-20A | NM-B | Check model specs |
| Mini-split (18-36k) | 240V | 12-10 AWG | 20-30A DP | NM-B | Check model specs |
| Whole-house fan | 120V/240V | 14-12 AWG | 15-20A | NM-B | Depends on motor size |
Heavy Load Circuits
| Equipment | Circuit | Wire Gauge | Breaker | Cable Type | Notes |
|---|---|---|---|---|---|
| Electric water heater | 240V | 10 AWG | 30A DP | 10/2 NM-B | Up to 5,500W |
| Electric dryer | 240V | 10 AWG | 30A DP | 10/3 NM-B | 4-wire (needs neutral) |
| Electric range | 240V | 6 AWG | 50A DP | 6/3 NM-B | 4-wire (needs neutral) |
| EV charger (32A) | 240V | 8 AWG | 40A DP | 8/2 NM-B | 80% rule: 40A breaker for 32A continuous |
| EV charger (48A) | 240V | 6 AWG | 60A DP | 6/2 THHN | 80% rule: 60A breaker for 48A continuous |
| Hot tub/spa | 240V | 6 AWG | 50A DP | THHN in conduit | GFCI required |
| Pool pump | 240V | 12-10 AWG | 20-30A DP | UF-B or conduit | GFCI required |
AWG Physical Dimensions and Cross-Sections
For those who need precise measurements for conduit fill calculations, wire identification, or engineering applications.
| AWG | Diameter (mm) | Diameter (in) | Cross-Section (mm²) | Cross-Section (kcmil) | Turns per Inch |
|---|---|---|---|---|---|
| 18 | 1.024 | 0.0403 | 0.823 | 1.62 | 24.8 |
| 16 | 1.291 | 0.0508 | 1.309 | 2.58 | 19.7 |
| 14 | 1.628 | 0.0641 | 2.081 | 4.11 | 15.6 |
| 12 | 2.053 | 0.0808 | 3.309 | 6.53 | 12.4 |
| 10 | 2.588 | 0.1019 | 5.261 | 10.38 | 9.8 |
| 8 | 3.264 | 0.1285 | 8.366 | 16.51 | 7.8 |
| 6 | 4.115 | 0.1620 | 13.30 | 26.24 | 6.2 |
| 4 | 5.189 | 0.2043 | 21.15 | 41.74 | 4.9 |
| 3 | 5.827 | 0.2294 | 26.67 | 52.62 | 4.4 |
| 2 | 6.544 | 0.2576 | 33.62 | 66.36 | 3.9 |
| 1 | 7.348 | 0.2893 | 42.41 | 83.69 | 3.5 |
| 1/0 | 8.252 | 0.3249 | 53.49 | 105.6 | 3.1 |
| 2/0 | 9.266 | 0.3648 | 67.43 | 133.1 | 2.7 |
| 3/0 | 10.40 | 0.4096 | 85.01 | 167.8 | 2.4 |
| 4/0 | 11.68 | 0.4600 | 107.2 | 211.6 | 2.2 |
How the AWG System Works
The AWG numbering system isn't arbitrary — it's based on the number of drawing dies the wire passes through during manufacturing. Each die reduces the diameter by a consistent ratio.
The mathematical relationship: Each step in AWG changes the diameter by a factor of 1.1229 (the 39th root of 92). Every 6 AWG steps doubles the diameter, and every 3 AWG steps doubles the cross-sectional area.
This means:
- 3 gauges smaller (e.g., 10 to 7 AWG) = 2× cross-section area = ~2× ampacity increase
- 6 gauges smaller (e.g., 12 to 6 AWG) = 4× cross-section area = ~2× diameter
- 10 gauges smaller (e.g., 14 to 4 AWG) = 10× cross-section area
The system goes from 40 AWG (0.003 inches, used in electronics) to 0 AWG (0.325 inches). Beyond 0 AWG, sizes are expressed as multiples of zero: 1/0, 2/0, 3/0, and 4/0 (pronounced "one-ought" through "four-ought"). Above 4/0, wire is measured in kcmil (thousands of circular mils) — 250, 300, 350 kcmil, etc.
Real-World Examples
Example 1: Wiring a New Central AC Installation
Scenario: You're installing a Carrier 24ACC636A003 (3-ton, 16 SEER2). The nameplate reads: MCA 19.0A, MOP 30A, 208/230V, 1-phase.
Wire sizing:
- MCA of 19.0A → Need wire rated for ≥19.0A
- 10 AWG copper at 60°C = 30A ✓ (exceeds MCA)
- MOP of 30A → Breaker = 30A double-pole
- Run length: 45 feet from panel → Voltage drop: (2 × 45 × 19 × 1.24) / 1000 = 2.1V = 0.9% ✓
Result: 10/2 NM-B from panel to disconnect, 10 AWG THHN in flex conduit from disconnect to unit, 30A double-pole breaker.
Example 2: Adding an EV Charger to an Existing Home
Scenario: You want to install a 48-amp Tesla Wall Connector in the garage, 60 feet from the panel.
Wire sizing:
- 48A continuous load → 48A × 1.25 = 60A breaker required (80% rule)
- 60A breaker requires minimum 6 AWG copper (55A at 60°C... wait, that's only 55A)
- Since the breaker is 60A and 6 AWG at 60°C is 55A, you need to verify: NEC allows 6 AWG on a 60A breaker because the next standard breaker size above 55A is 60A (NEC 240.4(B))
- Voltage drop at 60 ft, 48A, 6 AWG: (2 × 60 × 48 × 0.491) / 1000 = 2.83V = 1.2% ✓
Result: 6/2 NM-B or 6 AWG THHN in conduit, 60A double-pole breaker.
Example 3: Feeding a Detached Garage Sub-Panel
Scenario: You want a 60A sub-panel in a detached garage 120 feet from the main panel.
Wire sizing:
- 60A feeder → 6 AWG copper minimum (55A at 60°C, acceptable per NEC 240.4(B))
- Voltage drop at 120 ft, 60A, 6 AWG: (2 × 120 × 60 × 0.491) / 1000 = 7.06V = 2.9% on 240V ✓
- Need 4 wires: 2 hots + neutral + ground (separate building requires local grounding electrode)
- Underground run → Use THWN conductors in PVC conduit or direct-burial UF cable
Result: 6 AWG copper THWN in 1" PVC conduit (4 conductors), 60A double-pole breaker at main panel, ground rod at garage.
Example 4: Wiring a Tankless Water Heater
Scenario: Installing a Rheem RTEX-18 tankless water heater (18kW, 240V). It requires 2 × 40A circuits.
Wire sizing per circuit:
- 18kW ÷ 2 circuits = 9kW per circuit → 9,000W ÷ 240V = 37.5A per circuit
- Continuous load: 37.5A × 1.25 = 46.9A → 50A breaker per circuit
- 50A breaker → 6 AWG copper minimum
- Two separate 6/2 NM-B cables, each on a 50A double-pole breaker
Result: Two 6/2 NM-B cables, two 50A double-pole breakers, taking up 4 panel spaces total. This is why tankless electric water heaters often require a panel upgrade.
Key Takeaways
- 14 AWG = 15A, 12 AWG = 20A, 10 AWG = 30A — these NEC 240.4(D) caps are non-negotiable for branch circuits
- Use NEC Table 310.16 as your primary reference — the 60°C column for NM-B cable, 75°C for THWN in conduit
- Aluminum requires upsizing ~2 AWG compared to copper for equivalent ampacity
- Calculate voltage drop on any run over 50 feet — the 3% branch circuit limit catches many installations
- Temperature derating is critical for attic runs in hot climates and conduits with multiple conductors
- Always verify equipment nameplate — MCA determines wire size, MOP determines breaker size
- Copper costs 40–60% more than aluminum per amp of capacity — use aluminum for service entrance and large feeders where code allows
Frequently Asked Questions
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