Wire Gauge Calculator

Estimate AWG wire gauge, wire diameter, circular mils, ampacity, voltage drop, circuit watts, and load percentage from amps, voltage, wire distance, material, and phase type.

Calculate Wire Gauge

AWG gauge estimates are based on ampacity and voltage drop. Smaller AWG numbers mean larger wire.
Your result will appear here.

How the wire gauge calculator works

Load to gauge:
The calculator adjusts the load current if needed, then estimates a wire gauge that can support the amps and voltage drop target.

Gauge lookup:
Select a known AWG size to estimate diameter, circular mils, and simplified ampacity.

Voltage drop check:
The calculator estimates voltage drop over the entered distance for the selected or recommended wire gauge.

Why use a wire gauge calculator?

A wire gauge calculator helps estimate the AWG size needed for electrical planning and voltage drop checks.

It can help with branch circuits, low-voltage wiring, feeders, garage runs, shed wiring, RV circuits, solar wiring estimates, lighting circuits, and basic electrical project planning.

What your result means

Your result shows estimated wire gauge, ampacity, wire diameter, circular mils, voltage drop, voltage drop percent, adjusted current, watts, round-trip distance, and comparison scenarios.

Wire gauge calculator formulas

Frequently asked questions

What is wire gauge?

Wire gauge is a standard way to describe wire size. In the AWG system, smaller gauge numbers mean larger wire.

What gauge wire is commonly used for 20 amps?

For a basic copper branch circuit estimate, 12 AWG is commonly associated with 20 amps. Final sizing depends on code, insulation, terminals, distance, and installation conditions.

Why does wire distance matter?

Longer wire runs have more resistance, which can increase voltage drop. A larger wire gauge may be needed for longer distances.

Can this replace an electrician?

No. This calculator is a planning estimate. Always verify conductor size, breaker size, derating, temperature rating, terminals, conduit fill, and local code with a qualified electrician.