Home & DIY Calculators
Extension Cord Voltage Drop Calculator
Enter wire gauge, length, load current, and source voltage to calculate voltage drop and percentage.
2.96V drop (2.5%)
≈ 117.0V at the load end
3% or less is a commonly cited acceptable voltage drop for branch circuits. This is a planning estimate for copper conductors — for permanent household wiring, consult a licensed electrician and your local electrical code.
How to use this tool
- 1Select your wire's AWG gauge.
- 2Enter the one-way length in feet.
- 3Enter the load current in amps.
- 4Enter source voltage.
- 5See voltage drop and percentage.
Frequently asked questions
What voltage drop is considered acceptable?+
3% or less is a commonly cited acceptable threshold for branch circuits — higher drops can cause dimming, overheating, or reduced equipment performance.