Wire Size Calculator
Estimate a conductor size based on load, circuit voltage, cable length, and an allowable voltage-drop target.
Results
Enter your circuit details to estimate a wire size.
Preliminary voltage-drop estimate only.
How to use the calculator
- Select the current type, phase where applicable, conductor material, and cable-length unit.
- Choose whether to enter load power or current.
- Enter voltage, one-way cable length, and the maximum allowable voltage-drop percentage.
- Review the suggested wire size and estimated voltage drop.
Assumptions and limitations
This calculator estimates conductor size from voltage drop using approximate conductor resistance values and a simplified model. Cable length is entered as one-way distance; the calculation accounts for the return path on DC and single-phase circuits and uses a three-phase approximation for three-phase AC. The result does not verify ampacity, terminal temperature ratings, overcurrent protection, installation method, or electrical-code compliance. Real-world impedance, temperature, and installation conditions can change results. Consult a qualified electrician and applicable local electrical requirements before selecting or installing conductors.
