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.

Supply voltage

Required number input.

Forward voltage

Required number input.

Series resistor

Required number input.

Compute the current through an LED in milliamps given the supply voltage, forward voltage, and series resistor. 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]

LED current

The resulting led current returned as a number.

• LED forward voltage, current, power, efficacy, intensity, wavelength, and viewing angle depend on junction temperature, binning, drive waveform, optics, aging, and the manufacturer's measurement convention. Thermal design and absolute maximum ratings remain separate.
• 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.

• Zener Current

  Compute the current through a Zener diode in milliamps given the supply voltage, Zener voltage, and series resistor.

• LED Series Resistor Calculator

  Compute the series resistor that sets an LED operating point: R = (Vs - Vf) / I, dissipating the difference between supply and forward voltage.

• LED Forward Voltage Vs Current

  Shockley-diode forward voltage estimate from current, saturation current, ideality factor and junction temperature; series resistance omitted.