Wire Size Calculator
Estimate a minimum AWG conductor size from voltage-drop criteria for copper or aluminum circuits.
Why use this wire size calculator?
Wire Size Calculator selects the smallest listed AWG that satisfies the entered voltage-drop target using a circular-mil calculation.
Example
Enter voltage, current, one-way run length and a 3% drop target to get a voltage-drop-based AWG estimate.
Important note
The result is not a complete conductor-size determination. Ampacity, derating, fault protection, insulation and code requirements may require a larger conductor.
How to use it
Start with the inputs shown above, review any options or assumptions, then generate the result. Where the tool creates a file, keep the original until you have opened and checked the downloaded output.
Frequently asked questions
Is this tool free?
Yes. The core tool is free to use.
Do I need an account?
No. You can use it without signing up.
Does it work on mobile?
Yes. Toolbox is designed for modern mobile and desktop browsers.