About AmpWireSize

AmpWireSize is run by an independent publisher who builds free electrical calculation tools. There is no large company behind the site, no paid membership, and no account to create. The goal is simple: give homeowners, DIY installers, RV and boat owners, and students a clear answer to questions like "what wire size do I need for this load?" and "how much voltage will I lose over this run?"

How the calculations work

Every calculator is based on published material: standard wire ampacity tables, conductor resistance values, and well-known voltage drop formulas. Where a rule of thumb is used instead of a table value, the page says so. We aim to show the inputs, the formula, and the reference the result comes from, so you can check the work yourself rather than trusting a black box.

Methodology transparency

If a calculator ignores a factor, such as some temperature or bundling derating adjustments, the disclaimer on that page names it. If you find an error in a formula, a table value, or a unit conversion, corrections are welcome. A correction is only useful if it points to a source, so please include one when you can.

The tools are educational. They do not replace a licensed electrician, the National Electrical Code or your local code, or the instructions from the equipment manufacturer. Read the disclaimer before relying on any result, and see the privacy policy to learn how the site handles data and advertising.