Wire Size / Ampacity Calculator
Enter the load and run length below, then press Calculate. This tool checks both the NEC 75°C ampacity table and the voltage-drop limit you set, then recommends the larger (safer) wire size of the two.
Simple Contractor Tools
This calculator is an estimating aid for planning purposes only. It is not a substitute for a licensed electrician's judgment or for verification against the current NEC and your local electrical code before any work is performed or inspected.