Voltage Drop Calculator
Estimate conductor voltage drop, percentage loss and load voltage for copper or aluminum circuits.
Why use this voltage drop calculator?
Voltage Drop Calculator estimates conductor voltage loss using conductor material, circular-mil area, current, length and circuit type.
Example
Compare 10 AWG and 8 AWG on a long circuit to see how conductor size affects percentage voltage drop.
Important note
This is not an electrical-code or ampacity check. Temperature, installation method, conductor rating, protection and local rules require professional verification.
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.