AWG Wire Gauge Calculator
Wire diameter, resistance, current capacity, and voltage drop for any AWG — copper or aluminum.
Wire Selection
Voltage Drop
Wire Specifications
Voltage Drop
Cross-section (to scale vs AWG 4/0)
RESISTANCE PER METER VS AWG
Resistance per meter vs AWG (Copper)
AWG Reference Table
| AWG Gauge | Diameter | Cross-section | Resistance (Cu) | Max. Current |
|---|---|---|---|---|
| AWG 4/0 | 11.684 mm | 107.20 mm² | 160.80 µΩ/m | 260 A |
| AWG 3/0 | 10.405 mm | 85.03 mm² | 202.60 µΩ/m | 225 A |
| AWG 2/0 | 9.266 mm | 67.43 mm² | 255.40 µΩ/m | 195 A |
| AWG 1/0 | 8.252 mm | 53.49 mm² | 322.40 µΩ/m | 170 A |
| AWG 1 | 7.348 mm | 42.41 mm² | 406.50 µΩ/m | 150 A |
| AWG 2 | 6.544 mm | 33.63 mm² | 512.70 µΩ/m | 130 A |
| AWG 4 | 5.189 mm | 21.15 mm² | 815.20 µΩ/m | 95 A |
| AWG 6 | 4.115 mm | 13.30 mm² | 1.30 mΩ/m | 75 A |
| AWG 8 | 3.264 mm | 8.37 mm² | 2.06 mΩ/m | 55 A |
| AWG 10 | 2.588 mm | 5.26 mm² | 3.28 mΩ/m | 35 A |
| AWG 12 | 2.053 mm | 3.31 mm² | 5.21 mΩ/m | 25 A |
| AWG 14 | 1.628 mm | 2.08 mm² | 8.29 mΩ/m | 20 A |
| AWG 16 | 1.291 mm | 1.31 mm² | 13.17 mΩ/m | 13 A |
| AWG 18 | 1.024 mm | 0.8228 mm² | 20.95 mΩ/m | 7 A |
| AWG 20 | 0.813 mm | 0.5189 mm² | 33.31 mΩ/m | 5 A |
| AWG 22 | 0.644 mm | 0.3255 mm² | 52.92 mΩ/m | 3 A |
| AWG 24 | 0.511 mm | 0.2047 mm² | 84.08 mΩ/m | 2 A |
| AWG 26 | 0.405 mm | 0.1288 mm² | 133.90 mΩ/m | 1 A |
| AWG 28 | 0.321 mm | 0.0810 mm² | 212.90 mΩ/m | 0.8 A |
| AWG 30 | 0.255 mm | 0.0509 mm² | 338.60 mΩ/m | 0.5 A |
Max. current ratings are for single copper conductors in free air at 60°C insulation (NEC). Derate for bundled cables, conduit, or high ambient temperature.
AWG Wire Gauge Explained
AWG (American Wire Gauge) is the standard sizing system for electrical wire in North America. The system runs backwards: a higher AWG number means a thinner wire. AWG 4/0 is about 12mm in diameter, while AWG 30 is roughly the thickness of a human hair. Each decrease of 6 AWG approximately doubles the cross-sectional area of the wire.
Resistance per meter depends on the conductor's cross-section and material. Copper is the most common choice: it has low resistivity (1.724×10⁻⁸ Ω·m at 20°C), good flexibility, and easy soldering. Aluminum has about 61% of copper's conductivity, so a given AWG aluminum wire has roughly 1.64× more resistance than the same gauge in copper. Aluminum is cheaper and lighter, which is why it's used in overhead power lines.
Voltage drop matters most in long runs or high-current applications. A 0.5V drop is negligible for a 120V mains circuit, but it's catastrophic for a 3.3V microcontroller rail. The rule of thumb in residential wiring is to keep voltage drop below 3% of the supply voltage for branch circuits. For 12V automotive or marine systems, stay under 3% (about 360mV) to avoid relay chatter and motor issues.
Voltage Drop (round trip)
V_drop = 2 × I × R_per_m × LResistance (copper, 20°C)
R/m = ρ / A = 1.724×10⁻⁸ / A_m²Key Points
- Higher AWG number = thinner wire (inverse scale)
- Every 6 AWG steps doubles/halves the cross-section
- Aluminum resistance is ~1.64× higher than copper for same AWG
- Always calculate round-trip drop (2× the wire length)
- Derate current capacity for bundled cables and high temperatures
Applications
- Power wiring and circuit breaker sizing
- PCB trace current capacity estimation
- Automotive and marine wiring
- Solar panel and battery cable sizing
- Motor and transformer winding design
Wire Gauge Application Reference
| AWG | mm² | Max Current | Typical Application |
|---|---|---|---|
| AWG 8 | 8.37 | 40A | Subpanel feeds, EV charging |
| AWG 10 | 5.26 | 30A | Dryer, A/C units, hot tubs |
| AWG 12 | 3.31 | 20A | Kitchen outlets, bathroom |
| AWG 14 | 2.08 | 15A | General lighting & outlets |
| AWG 16 | 1.31 | 13A | Extension cords, light fixtures |
| AWG 18 | 0.82 | 10A | Lamp cords, low-voltage DC |
| AWG 20 | 0.52 | 7A | Automotive low-current, sensors |
| AWG 22 | 0.33 | 5A | Signal wiring, thermocouples |
| AWG 24 | 0.20 | 3A | Data buses, low-power MCU |
| AWG 26 | 0.13 | 2A | Breadboard jumpers, I2C/SPI |
| AWG 28 | 0.08 | 0.8A | Earbud cables, fine instrument |
| AWG 30 | 0.05 | 0.5A | Magnet wire, motor windings |
Worked Examples
NEC requires wire rated 125% of continuous load: 32A × 1.25 = 40A
Use AWG 8 copper in conduit. Run dedicated 240V / 40A circuit.
GPIO current: 16 mA per pin, 50 mA total. AWG 26 (2A rated) is more than sufficient.
Use AWG 22 for durability in prototyping environments.
Design Tip
For DC circuits, resistance matters more than ampacity.
R = ρ × L / A (ρ_copper = 1.68 × 10⁻⁸ Ω·m)Always derate to 80% of max current rating for continuous loads. In automotive: use wire rated for 105°C (not standard 60°C building wire).
Did you know? The American Wire Gauge (AWG) system works backwards — a larger AWG number means a thinner wire. AWG 0000 (4/0) is the thickest at ~11.7 mm diameter, while AWG 40 is about the thickness of a human hair at 0.08 mm.