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Daily build note · November 4, 2026

Idle Rig

Idle GPU earnings calculator: rental rate vs power bill vs marketplace fees vs wear, with monthly net profit, the break-even hourly rate, a waterfall chart, a two-card comparison and a worth-it verdict.

AI Tools Interactive demo live Static HTML/CSS/JS

What shipped

Idle Rig is an earnings calculator for renting out a GPU you're not using. Pick a card from consumer presets (RTX 5090 down to RTX 3060, plus a Radeon RX 7900 XTX) or workstation and datacenter presets (RTX A6000, L40S, A100, H100). Each preset fills in an hourly rental rate, GPU wattage and card value, and every one of those is an editable example assumption, not a market quote. Then set hours listed per day, occupancy (how much of that time someone actually rents it), your electricity price, the marketplace fee, a wear assumption (percent of card value lost per 1,000 rented hours), and the watts the rest of the system pulls when it's rented or sitting idle. You get monthly gross, fees, power bill, wear and net profit on a waterfall chart. You also get the break-even hourly rate, net per rented hour, yearly net, how long it takes to earn back the card, a "what if occupancy changes" strip at 25/50/75/100%, and a Worth it / Marginal / Not worth it verdict. Turn on Compare two cards to see them side by side. The whole setup is saved in the URL, so you can share it.

How to try

  • Start with the RTX 4090 default, then type the rate you actually see on a marketplace today into Rate $/h. The break-even rate tells you how far it could drop before you're paying to host.
  • Set electricity to the rate on your power bill. Try 0.30 to see how fast expensive power eats the margin.
  • Drag occupancy down to 20%. Idle draw while the card is listed but not rented starts to count, and the verdict can flip.
  • Hit Compare two cards, set card B to an older RTX 3090 or a datacenter card, then use Copy share link.

Why this (vs neighbors)

This comes from the Startup Opportunities list (#19, "Airbnb for idle GPUs": rent out computing power you're not using). Before anyone lists a card, they need to know whether the rental income beats the power bill, the platform's cut and the wear on the hardware. This build answers that one question honestly. It's the flip side of Server Closet, which asked whether to buy GPUs or rent them; this one asks what a card you already own can earn.

Scope trim

No live marketplace prices, no host signup, no benchmarking of your actual card, and no tax treatment. It runs on the numbers you type in, all in your browser.

Limitations

  • Preset rates, wattages and card values are rough examples. Rental prices move constantly, so check current marketplace prices before trusting the verdict.
  • Wear is a single assumption. Real wear depends on heat, fan hours and how much "used for rentals" knocks off resale.
  • It leaves out income tax, internet, extra cooling, hardware failures, payout minimums and the hassle of keeping a host online.

Suggested next steps

  1. Pull live price ranges from public marketplace listings into the presets, with a timestamp.
  2. Add time-of-use electricity rates so the card is only listed during cheap hours.
  3. Add a multi-GPU rig mode with shared system overhead.