Ω
LED Resistor Calculator
Calculate LED series resistor from supply voltage, forward voltage, and current.
Electrical engineering safety note
Electrical engineering calculators on ToolsBing are preliminary educational and planning tools only. Electrical work can create shock, fire, arc-flash, equipment damage, and code-compliance risks. Verify all calculations with licensed electricians, qualified engineers, manufacturer data, local electrical codes, protective-device requirements, and safety standards before installation or operation.
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Estimated result
Use for education, early planning, and comparison only.
Verify conductor ratings, breaker/fuse sizing, derating, grounding, environment, and local code requirements.
Formula and assumptions
Series resistor = (supply voltage − LED voltage) ÷ LED current
This calculator uses simplified electrical assumptions. Real systems may require derating, conductor temperature ratings, insulation type, installation method, short-circuit protection, coordination studies, power quality review, and licensed professional verification.