Estimate extension cord voltage drop, final voltage, voltage drop percentage, power loss, cord load, and cord gauge impact from amps, watts, voltage, cord length, and AWG size.
Load current:
The calculator uses entered amps or converts watts to amps using the supply voltage.
Cord resistance:
The selected cord gauge and material are used to estimate conductor resistance over the cord length.
Voltage drop:
The calculator estimates voltage lost in the cord and subtracts it from the supply voltage to estimate final voltage at the device.
An extension cord voltage drop calculator helps estimate whether a cord is too long or too small for a load.
It can help with power tools, outdoor equipment, temporary lighting, heaters, compressors, pumps, RV cords, garage work, jobsite cords, and general electrical planning.
Your result shows estimated voltage drop, voltage drop percent, final voltage, power loss, cord load percentage, estimated amps, watts, cord length, gauge, and comparison scenarios.
Yes. A longer extension cord has more resistance, which usually increases voltage drop at the device.
Yes. A lower AWG number means a larger conductor, which usually reduces voltage drop and handles more current.
Many planning estimates try to stay near 3% to 5%, but sensitive equipment, motors, and high-load tools may need a heavier cord or shorter run.
No. This is a simplified planning estimate. Always follow the extension cord label, equipment requirements, outdoor rating, grounding requirements, and safe-use instructions.