Is wire size the same as cable cross-section?

For US English search intent, wire size is usually selected as AWG or kcmil. Metric cross-section can be converted, but the public tool is oriented around AWG.

Why does distance affect wire size?

Longer conductors have more resistance, so voltage drop can force a larger wire even when ampacity alone would allow a smaller size.

Can this replace an electrician or local code?

No. It is a screening calculator, not a code-compliant design or installation instruction.

Wire Size Calculator

Estimate AWG wire size from current, voltage, run length, conductor material and allowable voltage drop.

Load details

Load power, W

System voltage, V

Phase

Power factor

Wire and run assumptions

Conductor material

One-way run length, ft

Maximum voltage drop, %

AWG sizing by ampacity and voltage drop

The English intent is not a literal cable cross-section translation. Users expect an AWG wire size estimate that screens both current-carrying capacity and voltage drop over a run.

V_{d r o p} = \frac{K I L F}{C M}

K is conductor constant, I current, L one-way length, F circuit factor and CM circular mil area.

% d r o p = \frac{V _{d r o p}}{V _{so u r ce}} \times 100

The selected conductor should stay within the chosen voltage-drop target.

Code boundary

Preliminary estimator only

This page is not an NEC compliance approval. Real installations require conductor type, insulation rating, terminal temperature, ambient correction, conduit fill, overcurrent protection and local code review by a qualified professional.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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