How the Voltage Drop Estimate Works
The calculator estimates conductor resistance from the selected AWG cross-sectional area and a standard material resistivity at approximately 20°C. It then applies a two-conductor factor for DC or single-phase circuits, or a square-root-of-three factor for a balanced three-phase estimate.
Formula and method
Conductor resistance ≈ resistivity × one-way length ÷ conductor area. DC / single-phase drop ≈ 2 × current × resistance. Balanced three-phase drop ≈ √3 × current × resistance. Percentage drop = voltage drop ÷ system voltage × 100.
Tips for better estimates
Use the actual one-way route length, not the round-trip cable length. Select the correct material, AWG, circuit type, and nominal voltage for an initial comparison.
Important limitations
This is a simplified resistive estimate and is not an electrical design or safety approval. Temperature, conductor insulation, installation method, reactance, terminals, code requirements, and protective devices are excluded. A qualified electrician must verify sizing.