Wire Gauge (AWG) & Voltage Drop Calculator
AWG
Wire Gauge (AWG) & Voltage Drop Calculator
Diameter, resistance and voltage drop for copper wire — pick a gauge or enter a custom length/current
Wire & Run
Wire Properties (this gauge)
Diameter
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Cross-section Area
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Resistance / meter
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Typical Free-air Ampacity*
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Voltage Drop Over This Run (round trip: out + return)
Loop Resistance
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Voltage Drop
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% of Supply
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Power Lost in Wire
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Quick Reference Table
| AWG | Diameter | Area | Ω / m | Ω / 1000ft | Ampacity* |
|---|
Formulas: diameter (mm) = 0.127 × 92^((36−AWG)/39); area = π/4 × diameter²; resistance/m = ρcopper / area,
using ρcopper = 1.68×10⁻⁸ Ω·m at 20°C.
*Ampacity shown is a commonly-cited rule-of-thumb for a single insulated conductor in free air at room temperature (light hobby/chassis wiring) — it is not an electrical code rating. Bundled wires, higher ambient temperature, or code-compliance work (house wiring, panels) require consulting the real NEC/IEC ampacity tables for your insulation type and installation method.
*Ampacity shown is a commonly-cited rule-of-thumb for a single insulated conductor in free air at room temperature (light hobby/chassis wiring) — it is not an electrical code rating. Bundled wires, higher ambient temperature, or code-compliance work (house wiring, panels) require consulting the real NEC/IEC ampacity tables for your insulation type and installation method.
