Calculate Power Dissipation (Watts)

Find how many watts a component dissipates so you can size it safely.

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Voltage (V)

Current (I)

Resistance (R)

Power (P)

Enter any two values and the other two are solved automatically

💡 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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