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.

Inductance (H)

Required number input.

Resistance (ohm)

Required number input.

Supply voltage (V)

Required number input.

Target current (A)

Required number input.

Calculate RL rise time to a target current. 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]

Time (s)

The resulting time returned as a number.

• Inductor calculations depend on core material, air gap, turns, frequency, waveform, temperature, DC bias, copper resistance, skin and proximity effects, fringing, and saturation definition. Small-signal inductance and nominal current rating may not describe switching operation.
• 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.

• RL Current Rise

  Compute the RL circuit current as it rises toward its steady-state value.

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  Calculate RC charging time to a target voltage.

• Relay Coil Inductance

  Calculate relay-coil inductance from measured coil resistance and RL electrical time constant using L=Rτ; contact mechanics are not included.