Power Dissipation Calculator
What actually heats up — linear regulators, diodes, MOSFETs and resistors, each with its own correct loss formula.
A linear regulator burns the entire voltage difference as heat — at 12→5 V it wastes more energy than it delivers; above ~1 W of drop-heat a buck module pays for itself instantly. MOSFET figure is conduction loss only — at high switching frequency add switching loss ≈ ½·V·I·(tr+tf)·fsw. Rectifier diodes in bridges conduct in pairs (double the loss), and Vf rises with current.
Power Dissipation Calculator computes the heat each device type actually generates, with the right loss formula per device — free, instant and private in your browser. Anyone deciding whether a part needs a heatsink — or a better topology use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About Power Dissipation Calculator
Power Dissipation Calculator computes the heat each device type actually generates, with the right loss formula per device using the standard engineering relation: LDO: (Vin−Vout)·I; diode: Vf·I; MOSFET: I²·Rds(on); resistor: I²R. Worked live: a 12→5 V linear regulator at 0.8 A burns 5.6 W — more heat than useful output power. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use Power Dissipation Calculator
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use Power Dissipation Calculator?
- ✓Implements the real formula — LDO: (Vin−Vout)·I — with the substitution shown, not a black box
- ✓Built for anyone deciding whether a part needs a heatsink — or a better topology
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate power dissipation?+
The heat each device type actually generates, with the right loss formula per device follows LDO: (Vin−Vout)·I; diode: Vf·I; MOSFET: I²·Rds(on); resistor: I²R. For example, a 12→5 V linear regulator at 0.8 A burns 5.6 W — more heat than useful output power. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Why does my linear regulator get scorching hot?+
It converts the entire voltage difference to heat: efficiency is just Vout/Vin. At 12→5 V that's 42 % efficient at ANY current. Above ~1 W of drop-heat, a $2 buck module pays for itself in heatsink, board space and reliability.
Which current do I plug in — average or RMS?+
Resistive losses (I²R: resistors, MOSFET conduction) need RMS; diode loss tracks AVERAGE current times Vf (plus a small resistive term). For PWM waveforms the two differ a lot — a 50 % duty square of 2 A peak is 1 A avg but 1.41 A RMS.
Is the Power Dissipation Calculator free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
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