Does the length field represent one-way distance or total round-trip?

The tool assumes copper conductor at 20°C with a resistivity of 0.0175 ohm·mm²/m. Actual conditions may require a larger conductor size.

Is the calculated wire size a final design recommendation?

No, the result is an estimate only. Users must verify ampacity, protection, terminations, and local electrical codes with a qualified professional before making any installations.

Can this calculator be used for aluminum wire or other materials?

The formula is calibrated for copper at 20°C. Aluminum or different conductor materials have different resistivities and ampacity tables, so the output would not be accurate without adjustment.

ElectricalTool Review

Wire Size Calculator

Provided bySmartCalcsmartcalc.top

Free wire size calculator for estimating copper conductor area from voltage, current, cable length, and permitted vol...

One of 3 options for Wire Size Calculator

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Electronics and circuits calculators electrical wire-gauge circuit-sizing ampacity voltage-drop code-compliant

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About this tool

What Wire Size Calculator does

The Wire Size Calculator on SmartCalc.top estimates the minimum cross-sectional area of copper conductor needed for a circuit based on input voltage, current, one-way cable length, and allowed voltage drop. Users receive a rounded result in square millimeters, with a reminder to verify the output against local electrical codes and additional factors like ampacity and termination methods. The tool is designed for quick estimates in home improvement, construction, and electronics projects where selecting the correct cable type is essential for safe power transmission.

Step by step

How to use the SmartCalc Wire Size Calculator

1
Enter the system voltage (V) of the circuit
2
Input the expected load current (A)
3
Specify the one-way length (m) from source to load
4
Set the maximum permitted voltage drop (%) and click Calculate
5
Review the rounded conductor area result and check local codes before installation

Is it right for you

Best for

DIY enthusiasts, electricians, and hobbyists who need a fast, free estimate of copper wire gauge for low-to-moderate load projects and want to cross-reference the result with local regulations.

Limitations

Assumes copper conductor at 20°C; aluminum or different temperatures require adjustment
Result is an estimate only; does not replace professional electrical design or local code compliance
Does not account for all installation factors such as conduit fill, ambient temperature, or termination ratings

Questions

Wire Size Calculator FAQ

Does the length field represent one-way distance or total round-trip?: The tool assumes copper conductor at 20°C with a resistivity of 0.0175 ohm·mm²/m. Actual conditions may require a larger conductor size.
Is the calculated wire size a final design recommendation?: No, the result is an estimate only. Users must verify ampacity, protection, terminations, and local electrical codes with a qualified professional before making any installations.
Can this calculator be used for aluminum wire or other materials?: The formula is calibrated for copper at 20°C. Aluminum or different conductor materials have different resistivities and ampacity tables, so the output would not be accurate without adjustment.

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