Cable Size Calculator

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Inverter110

Electrical Wire Size & Voltage Drop Calculator

Wire Gauge Calculator

Determine recommended AWG / metric sizes, voltage drop levels, resistance, and wire limits instantly.

Wire Material Copper (Cu) Aluminum (Al)

System Type Single-Phase AC / DC (2-wire) Three-Phase AC

System Voltage (V)

12V

24V

48V

120V

220V

240V

480V

Custom

V

Load Current (Amps)

A

Please enter a positive load current.

Cable Length (One-Way)

Feet Meters

Please enter a positive cable distance.

Maximum Allowable Voltage Drop (%) 1% 2% 3% (NEC Branch Standard) 5% (Feeder Circuit Limit) 10%

✓

Excellent Sizing! Voltage drop remains within safe limits.

Recommended Size (AWG)

AWG 12

American Wire Gauge

Cross-Sectional Area

3.31 mm²

Metric sizing equivalent

Voltage Drop (%)

1.45%

Max limit target

Voltage Drop (Volts)

1.74 V

At load threshold

Conductor Resistance

0.116 Ω

Total loop resistance

Power Loss

26.1 W

Dissipated as heat

Safe Conductor Limit

20 A

NEC safe capacity

Voltage Drop % vs. Cable Length (m)

AWG to Metric Cross-Sectional Area

Select AWG Size

Diameter

0.00 mm

Area

0.00 mm²

Metric Area (mm²) to AWG Converter

Enter Metric Area (mm²)

Please enter a valid metric area.

Nearest Lower AWG

AWG 14

Nearest Higher AWG

AWG 12

Specific Voltage Drop Calculator

Select Wire Size

One-way Distance (feet)

Current (Amps)

Circuit Voltage (V)

Material Copper Aluminum

Voltage Drop

0.00 V

Voltage Drop (%)

0.00%

Remaining Voltage

0.00 V

Cable Resistance Calculator

Select AWG Wire Size

Length (One-way)

Feet Meters

Material Copper Aluminum

Total Resistance

0.00 Ω

Calculated for loop distance

Resistance / Unit

0.00 Ω/km

Single conductor rate

Cable Ampacity & Temperature Limits

Select Wire Size

Conductor Material Copper Aluminum

60°C Limit (TW/UF)

15 A

75°C Limit (THWN)

20 A

90°C Limit (THHN)

25 A

AWG Wire Sizing Data Table

Standard AWG measurements for copper and aluminum wires at 20°C ambient.

AWG	Diameter (mm)	Area (mm²)	Copper Resistance (Ω/km)	Aluminum Resistance (Ω/km)

Wire Gauge Sizing Principles

Selecting appropriate conductor wire thickness is essential to maintaining overall energy efficiency and preventing severe safety hazards. Undersized cables risk creating thermal overloads, wire insulation degradation, and eventual structural electrical fires.

Determining Cable Gauge Requirements

AWG sizes determine electrical cross-sectional areas using an inverse scale. For example, AWG 4 can carry substantially more current than AWG 14. Standard geometric scaling ratio calculates diameter differences as follows:

\( d_n = 0.127 \times 92^{\frac{36-n}{39}} \text{ mm} \)

Material Characteristics

• Copper: Low resistivity (\(1.72 \times 10^{-8} \ \Omega \cdot m\)), excellent conductivity rating, and standard for internal household wiring.
• Aluminum: Higher resistivity (\(2.82 \times 10^{-8} \ \Omega \cdot m\)), requiring thicker gauge sizing but providing a cheaper, lighter alternative for overhead transmissions.

Frequently Asked Questions

What voltage drop limit is standard? +

The National Electrical Code (NEC) suggests a maximum of 3% voltage drop across standard branch loading, with a combined limit of 5% from service feeds.

Why do 12V and 24V solar inverter systems require thicker cables? +

Low voltage requires significantly more current to transmit equivalent load power. High currents combined with low voltage source potentials are highly sensitive to loop resistance voltage drops.