What a task costs on a box you own, rented, or through an API.
Put in the task, how often you run it and the machine you are thinking of. It gives you the cost per task each way, and when owning pays back.
- we measured it0 — numbers off our own runs — how fast a machine is, and what it draws
- we gathered it5 — prices read off somebody else’s published page, each with the day we read it
- we worked it out11 — the arithmetic, and the two assumptions it rests on
- yours9 — cells you fill. Each says what belongs there.
We have measured nothing in this sheet yet. The two rows that should be ours — tokens a second, and watts under load — are yours until our first run lands, and the sheet says so on the row rather than filling in a number we did not take.
The lesson that goes with it is still to be written — it lands on /ai/build in October 2026. The sheet does not wait on it.
It is not on sale yet — October 2026. Everything that goes into it is on this page, and the inputs are a free download below.
| What | Value | Where it came from |
|---|---|---|
| The task | yours What you actually run — "summarise a 40-page PDF", "tag a week of support mail". | |
| Runs a monthruns | yours How many times a month you run it. Everything below turns on this one. | |
| Tokens going in, a runtokens | yours Your prompt and whatever you attach to it — the document, the context, the examples. | |
| Tokens coming back, a runtokens | yours What the model writes back. Usually far smaller than what went in — and far dearer. | |
| The machine | yours The machine you are thinking of building or buying. | |
| Tokens a second, generatingtokens/s | yours How fast your machine writes the answer back, under load. Ours goes here the day our first run lands. No run is booked yet — until then, read it off your own machine. | |
| Watts the whole machine draws, under loadW | yours At the wall, not the card's rating — the meter charges for the whole machine. Ours goes here the day our first run lands. No run is booked yet — until then, read it off your own machine. | |
| Your pounds to the dollar£/$ | yours The rate your card actually gives you on the day. We do not gather exchange rates, so this one is yours. | |
| Electricity, a unit£/kWh | 0.2632 | we gathered it1 October – 31 December 2026 |
| Renting RTX-5090-32GB by the hour$/hr | 0.45 | we gathered it2026-09-18 |
| A million tokens INTO an API$ / 1M in | 0.1 | we gathered it2026-09-21 Google’s own price list — Gemini 2.5 Flash-Lite, standard tier, text in |
| A million tokens BACK from an API$ / 1M back | 0.4 | we gathered it2026-09-21 Google’s own price list — Gemini 2.5 Flash-Lite, standard tier, output including thinking |
| The card£ | 4,549.99 | we gathered it2026-09-21 |
| The rest of the machine£ | yours CPU, board, memory, power supply, case, storage — everything the card plugs into. No page we cite quotes it, and we will not put an estimate here and call it gathered. | |
| Years you keep ityears | 3 | we worked it out The life we write a machine down over. Change it and everything below follows. |
| What the card is worth at the endshare of list | 0.4 | we worked it out Our curve: the CARD falls in a straight line to two fifths of list over the life, and the rest of the machine to nothing. The used-card record replaces the first half once that line has rows. |
| Seconds a run, generatings | the sheet works it out | we worked it out Tokens coming back, divided by how fast your machine generates. It does not count the time spent reading your prompt — that is much faster, and nobody has measured it here, so the own-it and rented columns run a little light. |
| Electricity a runkWh | the sheet works it out | we worked it out Watts times seconds, turned into units. |
| What a run costs to power£ | the sheet works it out | we worked it out Units times the price of a unit. |
| The whole machine£ | the sheet works it out | we worked it out The card, plus the rest of it. |
| What the machine loses over its life£ | the sheet works it out | we worked it out The card, less what it is worth at the end, plus the rest of the machine written down to nothing. |
| Cost a task — your own machine£ | the sheet works it out | we worked it out Power for the run, plus the machine’s loss spread over every run of its life. |
| Cost a task — rented£ | the sheet works it out | we worked it out The generating seconds above, at the hourly rate, in your pounds. Same caveat: the time spent reading your prompt is not in it. |
| Cost a task — through an API£ | the sheet works it out | we worked it out Tokens in at the input price, plus tokens back at the output price, in your pounds. |
| Owning pays back inmonths | the sheet works it out | we worked it out The machine’s loss, divided by what you save each month against the cheaper of renting and the API. |
The rows the sheet works out are real formulas, so it recomputes the moment you change one of your own numbers. A sheet of frozen values would be a screenshot.