Power in a Resistor Calculator

Will that resistor cook?

Measure the voltage across the resistor itself, not the whole circuit. Everything is worked out in your browser. Nothing is saved or sent anywhere.

1. The resistor

2. Results

How it was worked out

    What this does and doesn't tell you

    • Resistors run hot near their rating. Doubling the rating keeps them cooler and longer-lived.
    • 240V AC mains can kill. In Australia, work on household mains wiring must be carried out by a licensed electrician. Low-voltage DC systems can still deliver very high current.
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