Wire Gauge Calculator

Calculate wire size, voltage drop, and ampacity for electrical circuits. Supports DC, single-phase, and three-phase systems.

System Configuration

System Type

Conductor Material

Length Unit

Calculation Type

Circuit Parameters

Current

Voltage

Distance (meters)

Max Voltage Drop

Typical: 3% for branch circuits

Derating Factor

Account for temperature, bundling

AWG Wire Reference Chart

AWG	Diameter (mm)	Area (mm²)	Ampacity (A)
14	1.628	2.081	15
12	2.053	3.309	20
10	2.588	5.261	30
8	3.264	8.367	40
6	4.115	13.300	55
4	5.189	21.150	70
2	6.544	33.631	95
1	7.348	42.410	110
0	8.251	53.475	125

Note: Lower AWG numbers indicate larger wire diameters. Standard maximum voltage drop is 3% for branch circuits per NEC guidance. Always consult local electrical codes for specific requirements.

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Determine the correct wire gauge for electrical circuits based on current, voltage, distance, and allowable voltage drop. This wire size calculator helps electricians, engineers, and DIY enthusiasts with electrical wire sizing for residential, commercial, and industrial applications. Whether you're working with DC, single-phase AC, or three-phase AC systems, this tool simplifies conductor sizing by calculating either the required wire size or analyzing voltage drop for a selected gauge. Use this electrical wire gauge calculator to ensure proper cable gauge selection that meets both ampacity requirements and voltage drop limits according to electrical codes.

How to Use Wire Gauge Calculator

Select Calculation Type

Choose between "Wire Size" to find the recommended gauge, or "Voltage Drop" to analyze a specific wire gauge. Select your system type (DC, AC 1-Phase, or AC 3-Phase) and conductor material (copper or aluminum). This wire size calculation tool works for residential wiring projects, industrial installations, and commercial electrical systems.

Enter Circuit Parameters

Input the current in amperes, system voltage, and wire run distance. For electrical wire sizing, specify the maximum allowable voltage drop percentage (typically 3% for branch circuits). For voltage drop analysis, select the wire gauge (AWG) you want to evaluate. The calculator uses standard wire gauge chart values to determine appropriate conductor sizing.

Review Results

The calculator displays the recommended wire gauge, actual voltage drop, power loss, total resistance, and effective ampacity. Results account for material properties, temperature effects, and optional derating factors for installation conditions. Use these values to verify your wire size selection meets both safety and performance requirements.

Calculator Features

⚡

Multiple System Types

Supports DC, single-phase AC, and three-phase AC systems with appropriate voltage drop formulas

🔌

Material Selection

Choose between copper and aluminum conductors with accurate resistivity values

📏

Wire Sizing

Automatically find the smallest wire gauge that meets both ampacity and voltage drop requirements

📉

Voltage Drop Analysis

Calculate voltage drop and power loss for any selected wire gauge

🌡️

Temperature Effects

Accounts for temperature-dependent resistivity changes

⚙️

Advanced Options

Include power factor, reactance, and derating factors for accurate AC calculations

Complete Function List

DC system voltage drop calculation:
Single-phase AC voltage drop with power factor:
Three-phase AC voltage drop with power factor:
Copper conductor resistivity (1.724 × 10⁻⁸ Ω·m at 20°C):
Aluminum conductor resistivity (2.826 × 10⁻⁸ Ω·m at 20°C):
Temperature coefficient correction:
AWG wire gauge selection (14 AWG to 0 AWG):
Ampacity ratings for standard wire sizes:
Voltage drop percentage calculation:
Power loss calculation (I²R):
Total loop resistance:
Effective ampacity with derating factors:
Optional reactance input for AC systems:
Derating factor for ambient temperature and bundling:
Distance unit conversion (meters and feet):

Common Calculations & Examples

Example 1: Household Circuit Wire Sizing

Problem: A 15A household circuit runs 30 meters at 120V. What wire gauge is needed for a maximum 3% voltage drop?

Steps:

Select "Wire Size" calculation type
Choose "AC 1-Phase" system type
Select "Copper" material
Enter current: 15 A
Enter voltage: 120 V
Enter distance: 30 m
Enter max voltage drop: 3%
Click "Calculate"

Result: Recommended: AWG 12 (voltage drop: ~2.8%)

Explanation: For a 15A circuit at 120V over 30m, AWG 12 wire provides adequate ampacity (20A) and keeps voltage drop below 3%. The calculator accounts for copper resistivity and the 2-wire (go and return) path in single-phase systems.

Example 2: Motor Circuit Analysis

Problem: A 25A motor circuit runs 50 meters at 240V using AWG 10 wire. What is the voltage drop?

Steps:

Select "Voltage Drop" calculation type
Choose "AC 1-Phase" system type
Select "Copper" material
Enter current: 25 A
Enter voltage: 240 V
Enter distance: 50 m
Select AWG: 10
Click "Calculate"

Result: Voltage drop: ~3.9V (1.6%)

Explanation: AWG 10 wire has a resistance of approximately 3.277 Ω/km. Over 50m (0.05 km) in a single-phase system, the voltage drop is 2 × 25A × 3.277 Ω/km × 0.05 km ≈ 3.9V, which is 1.6% of 240V - well within acceptable limits.

Example 3: Three-Phase Industrial Load

Problem: A 40A three-phase load runs 100 meters at 480V. Find the required wire gauge for 2% maximum drop.

Steps:

Select "Wire Size" calculation type
Choose "AC 3-Phase" system type
Select "Copper" material
Enter current: 40 A
Enter voltage: 480 V
Enter distance: 100 m
Enter max voltage drop: 2%
Set power factor: 0.95
Click "Calculate"

Result: Recommended: AWG 6 (voltage drop: ~1.9%)

Explanation: Three-phase systems use √3 (approximately 1.732) as the multiplier instead of 2, reducing voltage drop for the same current. AWG 6 wire provides 55A ampacity and maintains voltage drop below 2% over the 100m run.

Example 4: Aluminum Conductor Sizing

Problem: A 30A circuit uses aluminum wire over 75 meters at 240V. What gauge is needed for 3% drop?

Steps:

Select "Wire Size" calculation type
Choose "AC 1-Phase" system type
Select "Aluminum" material
Enter current: 30 A
Enter voltage: 240 V
Enter distance: 75 m
Enter max voltage drop: 3%
Click "Calculate"

Result: Recommended: AWG 8 (voltage drop: ~2.8%)

Explanation: Aluminum has higher resistivity than copper (2.826 × 10⁻⁸ vs 1.724 × 10⁻⁸ Ω·m), requiring larger wire for the same voltage drop. AWG 8 aluminum provides adequate capacity while meeting the 3% drop requirement.

Example 5: Solar Panel Wire Sizing

Problem: A 20A DC solar panel circuit runs 15 meters at 12V. Determine the appropriate wire gauge for 2% maximum voltage drop.

Steps:

Select "Wire Size" calculation type
Choose "DC" system type
Select "Copper" material
Enter current: 20 A
Enter voltage: 12 V
Enter distance: 15 m
Enter max voltage drop: 2%
Click "Calculate"

Result: Recommended: AWG 8 (voltage drop: ~1.9%)

Explanation: DC systems require careful wire size selection due to lower operating voltages. For this 12V solar application, AWG 8 copper wire ensures minimal voltage drop, maximizing power delivery to batteries or inverters. The larger conductor size compensates for the low voltage and prevents significant power loss.

Example 6: EV Charging Station Installation

Problem: A 50A electric vehicle charging circuit runs 20 meters at 240V. What wire gauge is required for a 3% maximum drop?

Steps:

Select "Wire Size" calculation type
Choose "AC 1-Phase" system type
Select "Copper" material
Enter current: 50 A
Enter voltage: 240 V
Enter distance: 20 m
Enter max voltage drop: 3%
Click "Calculate"

Result: Recommended: AWG 6 (voltage drop: ~2.7%)

Explanation: EV charging stations require proper conductor sizing to maintain charging efficiency. AWG 6 wire provides 55A ampacity, exceeding the 50A requirement, while keeping voltage drop at 2.7% - well within the 3% limit. This ensures optimal charging performance and prevents overheating.

What is AWG?

AWG (American Wire Gauge) is a standardized wire sizing system. Lower AWG numbers indicate larger wire diameters. For example, AWG 10 is thicker than AWG 12. This system provides consistent wire gauge standards used throughout North America for electrical conductor sizing.

How to calculate wire size for electrical circuits?

To calculate wire size, you need the circuit current (amperes), system voltage, wire run distance, and maximum allowable voltage drop percentage. This wire size calculator automates the process by considering material resistivity, temperature effects, and system type (DC, single-phase, or three-phase). The tool finds the smallest wire gauge that meets both ampacity and voltage drop requirements.

Why does voltage drop matter?

Excessive voltage drop reduces equipment performance, causes dimming lights, and can damage motors. It also wastes energy as heat (I²R losses). Most codes limit voltage drop to 3-5% for branch circuits. Proper electrical wire sizing minimizes voltage drop, ensuring devices receive adequate voltage for optimal operation.

What wire gauge do I need?

The required wire gauge depends on circuit current, voltage, distance, and allowable voltage drop. Use this wire gauge calculator by entering your circuit parameters - the tool will recommend the appropriate AWG size. Generally, higher current, longer distances, or stricter voltage drop limits require larger wire (lower AWG number).

What is the difference between copper and aluminum?

Copper has lower resistance (better conductivity) but higher cost. Aluminum is lighter and cheaper but requires larger wire sizes and proper terminations to prevent corrosion. Aluminum has about 61% of copper's conductivity, meaning you'll need approximately one size larger aluminum wire compared to copper for the same application.

How does three-phase differ from single-phase?

Three-phase systems use √3 (1.732) as the multiplier instead of 2, resulting in lower voltage drop for the same current. This is because three-phase power uses three conductors with 120° phase separation. When calculating wire size for three-phase systems, the reduced voltage drop often allows smaller conductor sizing compared to single-phase.

What is ampacity?

Ampacity is the maximum current a wire can safely carry continuously under specified conditions. It depends on wire size, insulation type, ambient temperature, and installation method. When determining wire gauge, both ampacity and voltage drop must be satisfied - the calculator ensures your selected wire meets both requirements.

How to read a wire gauge chart?

Wire gauge charts typically list AWG sizes alongside wire diameter, cross-sectional area, resistance per unit length, and ampacity ratings. Lower AWG numbers represent larger wires - AWG 10 is thicker than AWG 12. Charts may show different ampacity values based on insulation type (THHN, THWN, etc.) and installation conditions. This calculator incorporates standard wire gauge chart data for accurate sizing.

When should I use derating factors?

Apply derating when multiple conductors are bundled together, ambient temperature exceeds standard conditions (30°C), or installation method reduces heat dissipation. Derating factors typically range from 0.7 to 1.0. When calculating wire size, derating ensures the selected conductor can safely carry current under actual installation conditions, not just ideal laboratory settings.

Wire Gauge and Resistance

Wire resistance depends on three factors: material resistivity (ρ), length (L), and cross-sectional area (A). The relationship is R = ρL/A. Larger wire (lower AWG number) has more area, reducing resistance. Copper's resistivity at 20°C is 1.724 × 10⁻⁸ Ω·m, while aluminum is 2.826 × 10⁻⁸ Ω·m. Resistance increases with temperature due to the positive temperature coefficient. Understanding these relationships is essential for accurate electrical wire sizing and conductor sizing calculations. Wire gauge standards like AWG provide standardized diameters that make these calculations consistent across different manufacturers.

Voltage Drop Calculation

Voltage drop (Vd) occurs due to wire resistance. For DC and single-phase AC: Vd = 2IRL, where I is current, R is resistance per unit length, and L is distance. The factor of 2 accounts for the go and return path. For three-phase: Vd = √3 I (R cos φ + X sin φ) L, where φ is the power factor angle and X is reactance. Lower power factor increases voltage drop. When calculating wire size for electrical circuits, these formulas determine the minimum conductor size needed to maintain acceptable voltage levels at the load.

Ampacity Ratings

Ampacity is determined by wire's ability to dissipate heat. Standard ratings assume 30°C ambient temperature, single conductor in free air, and specific insulation types. Common AWG ampacities: 14 AWG = 15A, 12 AWG = 20A, 10 AWG = 30A, 8 AWG = 40A, 6 AWG = 55A. These values must be derated for higher temperatures or bundled conductors. Wire gauge charts typically display these ampacity ratings alongside wire diameter and resistance values. When determining wire gauge, both ampacity and voltage drop must be satisfied - the larger requirement governs the final wire size selection.

Power Loss and Efficiency

Power loss in wire equals I²R, where I is current and R is total resistance. This energy is converted to heat. Higher current or longer runs increase losses. Voltage drop and power loss are related: P_loss = I × Vd. Minimizing voltage drop improves efficiency and reduces operating costs, especially for high-current or long-distance circuits. Proper wire size calculation helps optimize electrical system efficiency by selecting conductors that balance cost and performance.

Wire Gauge Standards and Charts

The American Wire Gauge (AWG) system provides standardized wire diameters used throughout North America. Wire gauge charts display AWG numbers alongside corresponding wire diameters, cross-sectional areas, resistance values, and typical ampacity ratings. These charts are essential references for electrical wire sizing, but modern calculators like this tool automate the selection process by incorporating chart data with calculation formulas. Understanding wire gauge standards helps verify calculator results and ensures compliance with electrical codes that reference specific AWG sizes for different applications.

Electrical Conductor Sizing Principles

Electrical conductor sizing requires balancing multiple factors: current-carrying capacity (ampacity), voltage drop limits, mechanical strength, and cost. The National Electrical Code (NEC) provides guidelines for minimum wire sizes based on circuit protection, but voltage drop calculations often require larger conductors than minimum ampacity alone. When calculating wire size for electrical circuits, consider the full circuit path including both supply and return conductors. Temperature effects, installation method, and conductor bundling all influence the final wire gauge selection. This comprehensive approach ensures safe, efficient, and code-compliant electrical installations.

Wire Gauge Calculator

System Configuration

Circuit Parameters

AWG Wire Reference Chart

How to Use Wire Gauge Calculator

Select Calculation Type

Enter Circuit Parameters

Review Results

Calculator Features

Multiple System Types

Material Selection

Wire Sizing

Voltage Drop Analysis

Temperature Effects

Advanced Options

Complete Function List

Common Calculations & Examples

Example 1: Household Circuit Wire Sizing

Example 2: Motor Circuit Analysis

Example 3: Three-Phase Industrial Load

Example 4: Aluminum Conductor Sizing

Example 5: Solar Panel Wire Sizing

Example 6: EV Charging Station Installation

Tips for Using Wire Gauge Calculator

Frequently Asked Questions

Understanding Wire Gauge Calculator

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