Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

RMS current (A)

Required number input.

Resistance (Ω)

Required number input.

Compute resistive winding or conductor loss as I²R from RMS current and resistance at the relevant operating temperature. Output is watts; AC skin and proximity effects are not included unless already reflected in the supplied resistance. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Loss W

The resulting loss w returned as a number.

• Compact electronics formulas omit some combination of tolerances, temperature drift, bandwidth, loading, parasitics, noise spectrum, nonlinearity, clipping, calibration, layout, and device-specific limits. Typical datasheet values are not guaranteed limits.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

• Transformer Copper Loss at Load

  Sum primary and secondary winding I²R losses using RMS currents and operating-temperature resistances. Additional windings and AC resistance effects are not included.

• Transformer Winding DC Resistance

  Estimate DC winding resistance from conductor resistivity, total wire length, and copper cross-section: R=ρl/A. Supply resistivity at operating temperature; AC skin and proximity losses are excluded.

• Power Module Loss Conduction

  Estimate resistive power-module conduction loss as RMS current squared times hot on-state resistance; use the operating-temperature resistance.