Wire Size / AWG Calculator

The Wire Size / AWG Calculator determines the correct wire gauge for an electrical circuit so it carries current safely without excessive voltage loss. Enter your system voltage, load current, one-way distance, and allowable voltage drop, then select your circuit type, conductor material, wire temperature rating, and installation type to get the recommended AWG wire size. Secondary outputs include actual voltage drop percentage, voltage drop in volts, and required circular mils.

V
A

The amperes drawn by the load

ft

Length of cable run in feet

%

Maximum allowable voltage drop percentage

Results

Recommended Wire Size

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Actual Voltage Drop

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Voltage Drop (Volts)

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Required Circular Mils

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Frequently Asked Questions

What is AWG and how does wire gauge affect electrical circuits?

AWG (American Wire Gauge) is a standardized system for wire sizing. Smaller AWG numbers indicate larger wire diameters. Proper wire gauge ensures adequate current carrying capacity and minimizes voltage drop, preventing overheating and power loss.

How much voltage drop is acceptable in electrical circuits?

The National Electrical Code (NEC) recommends maximum voltage drop of 3% for branch circuits and 5% for feeders. Lower voltage drop is better for equipment performance and energy efficiency.

What's the difference between copper and aluminum conductors?

Copper has lower resistance and better conductivity than aluminum, requiring smaller wire sizes for the same current. Aluminum is lighter and less expensive but requires larger gauges to carry equivalent current safely.

Why does wire temperature rating matter for sizing calculations?

Higher temperature ratings (60°C, 75°C, 90°C) allow wires to carry more current safely. The temperature rating affects the ampacity tables used to determine minimum wire size requirements.

How does installation type affect wire sizing?

Installation method affects heat dissipation. Wires in conduits retain more heat and may need larger sizes, while free air installations allow better cooling and smaller wire sizes for the same current.

What happens if I use undersized wire for my circuit?

Undersized wire can cause excessive voltage drop, reduced equipment performance, overheating, increased fire risk, and potential code violations. Always use the calculated minimum size or larger.

Do single-phase and three-phase circuits require different wire sizing?

Yes, three-phase circuits are more efficient and typically require smaller conductors for the same power load due to the balanced nature of three-phase power systems.

Should I always use the exact calculated wire size?

Use the calculated size as the minimum requirement. It's often wise to go one size larger for future load growth, reduced voltage drop, and improved system performance.