Stable Diffusion

Stable Diffusion is Stability AI’s image model family, and unlike most consumer image generators it is not sold as a simple monthly plan. Access runs through a developer API priced in credits, where one credit costs one cent, and different models and quality levels cost a different number of credits per image.

Stable Image Ultra, the flagship service, costs 8 credits per image. Stable Diffusion 3.5 Large costs 6.5 credits, and a Turbo variant of the same model is cheaper and faster in exchange for some quality. At $0.01 a credit, that puts a single Ultra image at roughly 8 cents, which is genuinely useful to know if you are estimating cost at volume rather than evaluating a single generation.

This is a developer product, not a consumer app

Twenty-five free credits come with signup, enough to test the API and see whether the model quality suits your use case before committing to anything. But there is no polished consumer interface here in the way Midjourney or DALL-E offer one; this is infrastructure meant to be integrated into somebody else’s product.

The self-hosted licensing option is the detail that separates Stability AI from most of its hosted-only competitors. A company with the infrastructure and legal requirement to run models on its own hardware, rather than sending data to a third-party API, has that option here in a way it usually does not elsewhere.

Where to be careful

Credit costs are stated per model and change as new models ship, so budget estimates need rechecking against the current pricing page rather than assumed to hold. And because this has no consumer front end, evaluating it means writing code against the API rather than clicking around an interface, which is a real barrier if you were expecting something you could try in a browser tab.