Last updated: 2022-05-01

Calculate Voltage Drop

Resistance from Wire and Load Cause Voltage Drop Along Wire

The higher the current draw through a wire, the greater the voltage drop. Larger wire size (diameter), measured as “American wire gauge” (AWG) the lower the voltage drop. Larger wire size offers less resistance to current for the load (watts) on the circuit. It is important to size wires according to voltage and load to minimize and control voltage drop. The path of least resistance is larger wire size.
Calculate Voltage Drop A larger diameter wire size results in less voltage drop. #10 AWG is larger diameter than #14 AWG.


Enter Volts


Total Watts – sum the wattages of every lamp along the cable length.
Enter Total Watts


One-way circuit length in feet. If you bought 100 feet of landscape lights wire and have 10 feet left over. Enter 90 feet.
Enter Cable Length in feet


Wire Size

Voltage Drop and Wiring Size

Voltage drop is not the issue it used to be using incandescent and halogen.
LED light source uses 5 to 7 times less power on the wire, that equates to 5 to 7 times less voltage drop.
Voltage drop is still a concern for optimum results when using more than a few lights, and you reach over 50 watts.
The wire size used can affect system performance.

Voltage Drop

Power loss occurs from watts used by lights, some loss is from wire resistance. Power loss on the wire; Voltage drops as wattage increases.
image showing voltage drop on wire with load