Electrical Wiring Calculator — Calculate Wire Size, Voltage Drop & Ampacity

Electrical Wiring Calculator

Calculate proper wire size, voltage drop, and ampacity for electrical wiring projects. Understand NEC requirements and ensure safe electrical installations.

Step 1: Circuit Parameters

20A

Understanding Circuit Parameters

System voltage determines the electrical pressure. Circuit current (amps) is the load requirement. Longer wire runs may require larger wire sizes to compensate for voltage drop.

Step 2: Wiring Details

86°F

About Wire Materials

Copper has better conductivity but is more expensive. Aluminum is lighter and cheaper but requires larger wire sizes for the same current capacity. Always follow NEC guidelines for proper installation.

Wiring Calculation Results

Summary
Wire Comparison
Voltage Analysis

Recommended Minimum Wire Size

12 AWG
Copper THHN/THWN-2
Voltage Drop
2.1V (1.8%)
Max Ampacity
25A
NEC Required Size
12 AWG
Wire Cost Estimate
$45-65

Wire Size Comparison

Wire Size (AWG) Copper Ampacity Aluminum Ampacity Voltage Drop Cost per 100ft

Voltage Drop Analysis

Voltage Drop Formula

VD = (2 × K × I × L) / CM

VD = Voltage Drop, K = Material Constant, I = Current (Amps), L = Length (ft), CM = Circular Mils. For single phase circuits, the factor 2 accounts for the round trip distance of the circuit.

Need Professional Electrical Advice?

Connect with our licensed electricians for detailed wiring solutions, code compliance guidance, and safe installation practices for your electrical projects.

Get Professional Advice