About Voltage Drop Calculator
Calculate line voltage drop and wire power loss for AC and DC circuits.. Designed for accurate, instantaneous calculations with zero wait time.
Formula
Voltage Drop = (2 × K × I × L) / Circular Mils (Copper constant K = 12.9)
Example Calculation
A 20A load on 12 AWG copper over 100 feet at 120V experiences ~7.9V drop (6.6%).
How to Use
- Enter your values into the form fields above.
- The calculation updates immediately in real time.
- Inspect the main summary and secondary breakdowns below.