Calculate Power Dissipation (Watts)
Find how many watts a component dissipates so you can size it safely.
💡 Ohm's law: V = I × R. Power adds P = V × I. Knowing any two lets you derive the rest — handy for sizing resistors, checking LED current, or working out heat dissipation.
Power tips
Enter voltage and current (or resistance) and the power in watts is solved automatically.
Resistors come in power ratings (1/4W, 1/2W, 1W…) — pick one rated well above the dissipated power.
A part running near its power limit gets hot and ages fast; aim for at least 2× headroom.
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