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.

Voltage Volts (V)

Required number input.

Armature Resistance Ohms (Ω)

Required number input.

Approximate DC motor stall current from applied voltage and armature resistance, neglecting brush and supply losses. 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]

Stall Amperes (A)

The resulting stall amperes returned as a number.

• Motor constants, current, torque, speed, reactive power, and propeller thrust depend on winding temperature, controller, supply sag, losses, saturation, load curve, airflow, and operating point. Nameplate constants and ideal propeller laws need test data for final sizing.
• 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.

• Dc Motor Armature Current

  Calculate DC motor armature current from applied voltage, back EMF, and winding resistance using the steady-state armature equation.

• Motor Starting Current

  Estimate DC motor current at startup as applied armature voltage divided by winding resistance, before back EMF develops; drive current limiting is excluded.

• Contactor Coil Current

  Calculate DC contactor-coil steady current from applied voltage and DC coil resistance; do not use this for AC inrush or inductive impedance.