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.

Primary RMS current (A)

Required number input.

Primary resistance (Ω)

Required number input.

Secondary RMS current (A)

Required number input.

Secondary resistance (Ω)

Required number input.

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

Primary Loss W

The resulting primary loss w returned as a number.

Secondary Loss W

The resulting secondary loss w returned as a number.

Total Copper Loss W

The resulting total copper loss w returned as a number.

• Transformer ratios and losses depend on waveform, frequency, core material and flux, turns, winding resistance, leakage, magnetizing current, load power factor, temperature, insulation, and construction. Ideal turns-ratio equations do not establish regulation or thermal rating.
• 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.

• Copper Loss

  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.

• 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.

• Transformer Total Loss

  Add winding copper, core iron, and other measured transformer losses in watts. This is a loss budget sum, not an efficiency estimate without input or output power.