Calculation worksheet
Voltage drop estimate
Estimate voltage drop from conductor size, material, current, and one-way length.
Enter your values and select Calculate to see a step-by-step result.
Reference2023 NEC Chapter 9, Table 8; 210.19(A)(1) Informational Note
Approximation using K = 12.9 (copper) or 21.2 (aluminum). Temperature, power factor, and AC impedance can change actual voltage drop; verify with conductor data.