Step-by-step walkthrough
Use this companion guide beside the interactive calculator to make sure you understand the “why” behind every click. Each section includes the classroom explanation, student-friendly language, and quick practice prompts.
Collect the data points listed below and double-check their units. Keeping an organized “givens” list is one of the fastest ways to reduce math errors and impress exam graders.
Step 1
Measure the one-way distance from the source to the load — the calculator accounts for the return path automatically.
Step 2
Enter the load's expected current draw and your target maximum drop (3% is a common guideline for branch circuits, 5% for feeders).
Step 3
Compare the table of gauges and drops; pick the recommended gauge or size up if the run may see more current later.
No. This estimates voltage drop from wire resistance for planning purposes. Building wiring must also meet ampacity, insulation, and code requirements — check the NEC tables or a licensed electrician for anything permanent or safety-critical.
Aluminum has roughly 1.6× the resistivity of copper, so it needs a larger cross-sectional area (a lower AWG number) to carry the same current with the same voltage drop.
