Every team I've worked with hits the same argument about three months after shipping something on top of an LLM: "Should we still be paying per token, or should we just self-host?"
And it's always argued on vibes. Someone read a blog post. Someone else got burned by a GPU bill once. Nobody's actually done the math. So here's the math — or at least the shape of it.
Paying an API has one killer advantage that people forget to give it credit for: you pay for exactly what you use, and nothing when you're idle. No GPU sitting warm at 3am doing nothing. No serving stack to babysit. If your volume is low or spiky, this is basically unbeatable, and honestly you should stop reading and just use the API.
Self-hosting flips that. You take on a mostly fixed cost — the GPU (rented or amortised) plus the very real human cost of running it — and in exchange, each extra token is almost free once you've paid for the box.
So the whole decision collapses to one question: at your volume, has that fixed cost dropped below what the meter would've charged you? That's the break-even. Everything else is just inputs to it.
Self-hosting quietly adds: fine-tuning experiments, storage and egress, eval infrastructure, and your engineers' time — which is not free, no matter how much they enjoy it.
The API quietly adds: price changes and rate limits you don't control, and the awkward bit — your data (and your customers' data) leaving your walls.
There's a second crossover that has nothing to do with dollars. If you handle regulated or client-confidential data, self-hosting wins the moment that data would otherwise be shipped off to a third-party API — full stop, whatever the token math says. When "our data can't leave our infrastructure" is a hard rule, you've already made the decision; you're just backfilling the spreadsheet.
The model is simple. The arithmetic — 12 months, amortisation, utilisation — is annoying. So we built the boring part: the LLM Cost Calculator charts API vs self-hosting over a year, no signup, no email wall.
When does self-hosting get cheaper? When your fixed cost (GPU amortisation + ops time) drops below the per-token meter at your sustained volume. Low/spiky → API. High/steady → self-host.
What's the cost everyone forgets? Engineers' time to run the stack. It's usually the single biggest hidden line.
Is an open model as good as a frontier API? Not automatically — decide your quality tier before you compare price, or you're comparing a Civic to a truck.
I'm genuinely curious where real teams land on this — what was your actual break-even, and did self-hosting turn out cheaper than you expected, or way more of a headache? Tell me in the comments.