Here is a fact that surprises many new home miners: essentially 100% of the electricity a mining PC consumes ends up as heat. Not most of it - effectively all of it. Understanding why is not just physics trivia; it is the foundation of reasoning honestly about what mining costs and where that cost goes.

The physics, briefly

A computer does not store energy or send it anywhere it can be recovered. The electricity that enters it powers transistors switching billions of times a second, spins fans, and lights LEDs - and every one of those processes ultimately dissipates its energy as heat into the surrounding air. The tiny fraction that leaves as light, sound, or data is negligible. By conservation of energy, watts in equals heat out. A 400W rig is, thermodynamically, a 400W heater that happens to compute.

Why this is useful, not depressing

At first "all the power becomes heat" sounds like total waste. It is not, for two reasons. First, the heat is a genuine by-product you can sometimes use - in winter it offsets your heating. Second, it makes the cost perfectly predictable: there are no hidden losses to chase, because the energy accounting is complete the moment you know the wattage.

The seasonal swing it creates

  • Winter: the heat substitutes for heating you would have paid for, so the effective cost of mining can drop sharply or even approach zero against electric heating.
  • Summer: the same heat must be removed by air conditioning, which spends additional energy, so the effective cost roughly doubles.

This single fact - all power becomes heat - is why home mining economics swing so hard with the seasons, and why thoughtful miners change their hours accordingly.

It also explains your room temperature

If a rig makes a small room noticeably warmer, that is not a malfunction; it is the expected behaviour of a few-hundred-watt heater. A 400W rig outputs about 1,365 BTU/hr, enough to lift a closed 10-by-12 room several degrees over a few hours. Planning where to put the rig is really planning where you want that heat to go.

The takeaway for honest accounting

Because the energy story is complete - watts in, heat out, nothing hidden - you can cost mining with confidence using nothing more than measured wattage and your rate. There is no mysterious extra draw, no unaccounted loss. That completeness is what makes grounded, hype-free home mining possible: the numbers add up exactly, every time.