Wire Gauge Calculator
Calculate the correct American Wire Gauge (AWG) size for your electrical projects. Determine wire size based on current, voltage, distance, and installation conditions.
Step 1: Electrical Parameters
About Voltage Drop
Voltage drop is the reduction in voltage in an electrical circuit between the source and load. For most applications, a 3% voltage drop is acceptable. Critical circuits may require 1% or less.
Step 2: Installation Conditions
Installation Factors
Wires in conduit or bundled together cannot dissipate heat as effectively as single wires in free air, requiring larger gauge sizes for the same current. Aluminum wires require larger gauges than copper for equivalent current capacity.
Wire Size Results
Recommended Wire Size
AWG Size Comparison
| AWG Size | Diameter (mm) | Area (mm²) | Ampacity (Copper) | Max Length* |
|---|
*Max length for 20A at 120V with 3% voltage drop
Technical Details
Wire Gauge Formula
AWG Calculation Formula
Wire size is determined by: 1) Calculate maximum allowable resistance based on voltage drop, 2) Determine cross-sectional area needed, 3) Select standard AWG size that meets requirements, 4) Check against ampacity tables for safety.
Formula: Area (mm²) = (2 × ρ × L × I) / (V_drop × V_system) × 1000
Where ρ = resistivity, L = length, I = current, V_drop = allowed voltage drop percentage
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