Wire Resistance Calculator
Calculate the electrical resistance of a wire based on material, length, and gauge.
Supports imperial and metric units.
Wire Resistance
Wire resistance formula:
R = ρ × L / A
Where:
- R = resistance (ohms)
- ρ = resistivity of material (Ω·m)
- L = wire length (meters)
- A = cross-sectional area (m²)
Material resistivity at 20°C:
- Copper: 1.68 × 10⁻⁸ Ω·m
- Aluminum: 2.65 × 10⁻⁸ Ω·m
- Steel: 1.43 × 10⁻⁷ Ω·m
Common AWG sizes and areas:
| AWG | Diameter (mm) | Area (mm²) |
|---|---|---|
| 10 | 2.59 | 5.26 |
| 12 | 2.05 | 3.31 |
| 14 | 1.63 | 2.08 |
| 16 | 1.29 | 1.31 |
| 18 | 1.02 | 0.823 |
Voltage drop: V_drop = I × R (current × resistance). Keep voltage drop under 3% for branch circuits.