Wire Size Calculator
Estimate the minimum cable size from current, length, supply voltage, and allowable voltage drop.
How This Wire Size Calculator Works
This tool estimates a practical minimum cable cross-sectional area based on voltage-drop criteria. It uses standard resistivity values at 20 C: copper = 0.017241 ohm mm2/m, aluminum = 0.0282 ohm mm2/m.
The formula basis is:
Single phase: Vdrop = I * (2 * rho * L / A)
Three phase (balanced): Vdrop = sqrt(3) * I * rho * L / A
The calculator computes the required area and then suggests the next standard cable size. Use this as a preliminary estimate and always verify with local wiring standards, thermal limits, installation method, and protection requirements.