🧰
Little Pocket Apps
Electrician Suite
Professional Tools — Free

Voltage Drop Calculator

Will the voltage hold up at the end of a long run? Put in the load, the distance and the wire, and see the drop before you pull a single foot of cable.

The Run
▾
amps
ft
▾
▾

Voltage Drop Result

Voltage drop
Voltage drop, percent
Voltage at the load

The 3% guide: the NEC recommends no more than 3% drop on a branch circuit (5% total from service to load). It is a recommendation, not a hard code rule, but inspectors and good practice treat it as the line.