Wire gauge calculator for AWG and voltage drop

A free browser-based wire gauge calculator that recommends the correct AWG wire size based on current, distance, and maximum allowable voltage drop. Supports copper and aluminum wires, includes AWG-to-mm² conversion, ampacity reference table, and practical presets for LED strips, outlets, EV chargers, and solar panels.

How to Calculate Wire Gauge

Enter current and distance

Set the load current in amps, one-way wire distance in meters or feet, and system voltage.

Set voltage drop limit

Choose the maximum acceptable voltage drop (typically 3% for branch circuits, 5% for feeders).

The AWG gauge, the cross-section and the voltage drop

See the recommended AWG gauge, cross-section in mm², actual voltage drop, and power loss in the wire.

Select the optimal wire size based on current, distance, and voltage drop

Current (A)

System Voltage (V)

One-Way Distance

Max Voltage Drop (%)

Wire Material

Recommended Wire

AWG Gauge

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Cross Section

—

Diameter

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Voltage Drop

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Drop %

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Power Loss

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Quick Presets

AWG ↔ mm² Converter

AWG

⇄

mm²

AWG Reference Table

Features

Calculate recommended AWG by current, distance, and max voltage drop for copper and aluminum

Accounts for aluminum carrying roughly 61% more resistance than copper, so it suggests a larger gauge where needed.

Bidirectional AWG ↔ mm² converter with wire diameter and resistance per kilometer

Converts either way and lists diameter and Ω/km — for example AWG 10 ≈ 5.26 mm² and AWG 14 ≈ 2.08 mm².

Voltage drop calculator showing actual drop in volts and percent for the full circuit

Uses Vdrop = 2 × I × R × L to count both supply and return conductors, then reports drop in volts and as a percentage.

Ampacity reference table (AWG 0000 to 40) with NEC-based current ratings

Covers gauges from 4/0 down to 40 with continuous current limits aligned to NEC ampacity figures.

FAQ

What is AWG?

American Wire Gauge — a standardized system for wire diameters. Lower AWG = thicker wire. AWG 10 ≈ 5.26 mm², AWG 14 ≈ 2.08 mm². Used primarily in North America.

How is voltage drop calculated?

Vdrop = 2 × I × R × L, where I is current, R is resistance per meter, L is one-way distance. Factor of 2 accounts for the round trip (supply + return wire).

What voltage drop is acceptable?

NEC recommends max 3% for branch circuits and 5% total (feeder + branch). For 12V DC systems, even 3% (0.36V) can affect LED brightness, so use thicker wire.

Copper vs aluminum — which to use?

Copper has 61% lower resistance and is standard for most wiring. Aluminum is cheaper and lighter but requires larger gauges and special connectors to prevent corrosion.

What is ampacity?

The maximum current a wire can carry continuously without exceeding its temperature rating. Depends on wire gauge, insulation type, ambient temperature, and installation method.

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Who is this tool for?

🔌 Electronics Enthusiasts

Published 06 Apr 2026 Updated 01 May 2026 Author: The Supreme