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Voltage Drop Calculator
Estimate conductor performance on longer runs, flag the common 3% planning threshold, and suggest the minimum wire size that gets back under target.
Enter wire size, length, current, and source voltage to estimate drop.
What the result means
Use the output correctly
- This estimate assumes a simple two-conductor loop.
- It is useful for branch-circuit planning, feeders, AV installs, and low-voltage runs.
- It does not replace full design checks for ambient correction, bundling, conduit fill, or local code requirements.
Related tools
Jump to supporting references
FAQ
Voltage-drop planning
Why suggest a minimum wire size automatically?
Because the fastest job-site answer is usually, “what do I need to go up to so this run stays sane?” The suggestion keeps that answer immediate.
Why show both 3% and 5% signals?
The 3% branch-circuit target is the common line in the sand, but installers often also want to know whether they still stay under the broader 5% total recommendation.