Last updated: 2026-11-06

Extension Cord Gauge Calculator

Extension cord gauge calculator: find the right wire gauge (AWG) for your cord length and amps, and check the voltage drop for tools, appliances, and outdoor equipment.

Calculate power loss and voltage drop in extension cords for your high-power appliances and tools. The numbers matter because undersized cords damage equipment and are a fire hazard.

Key Features

Real-time power loss and voltage drop calculation
Heat generation analysis for safety
Cost impact assessment for energy waste
Support for common household appliances
Wire gauge recommendations based on load
Safety alerts for risky configurations
Customizable power and length settings

Cord Specifications

Wire Gauge (AWG)

Cord Length (feet)

Load Details

Common Appliances

Custom Power (watts)

Input Power: 1000.0WVoltage Drop: 2.1%

14 AWG × 50ft

Power Loss: 21.33W

Efficiency: 97.9%

Voltage Drop

2.1%

Within safe limits

Yearly Cost

$4.36

Based on 4h daily use

Heat Generation

72.7 BTU/h

From power loss

Guide

What gauge extension cord do I need, and how much voltage will it drop?

The worked version of this calculator: a 1,500 W heater on 50 ft and 100 ft cords, gauge by gauge — including why 14 AWG can pass the ampacity check and still drop 6.40% of the voltage.

Read the guide