The short answer
Stability AI is billed per image, credit-based ($0.03-0.08). It has a free tier: 25 free credits (~$0.25) on signup. Paid usage is quoted by the vendor rather than listed as a public price.
Plans and prices
| Plan | Price | What it covers |
|---|---|---|
| Stable Image Ultra | $0.08 / image (8 credits) | Flagship text-to-image built on SD3.5, highest quality output. |
| SD3.5 Large | $0.065 / image (6.5 credits) | 8B-parameter model, 1MP output, text-to-image and image-to-image. |
| SD3.5 Large Turbo | $0.04 / image (4 credits) | Distilled, faster variant of SD3.5 Large for lower latency. |
| SD3.5 Medium / Stable Image Core | $0.035 / $0.03 per image | Medium = 3.5 credits; Core = 3 credits, the cheapest fast generation endpoint. |
| Edit & Control services | $0.05 / op (5 credits) | Inpaint, erase, remove-background, search-replace, and sketch/structure/style control. |
| Upscalers | $0.02-$0.60 / op (2-60 credits) | Fast (2cr), Conservative (40cr), Creative (60cr) upscaling tiers. |
How Stability AI bills you
The pricing model is per image, credit-based ($0.03-0.08). First-party API for the Stable Diffusion / Stable Image family with simple per-image credit pricing and instant self-serve trial credits. Best suited to: direct stable diffusion / stable image api.
What to watch for on the bill
- No public status page or formal uptime SLA on the self-serve API tier
- Stable Image Ultra at $0.08/image sits at the expensive end of hosted text-to-image APIs
The pricing page we read
Source: https://platform.stability.ai/pricing. Prices change, so confirm there before you commit.
Compare Stability AI with alternatives
Other image generation apis: OpenAI Images (gpt-image), Google Imagen / Gemini Image, fal.ai, Replicate, Black Forest Labs (FLUX).
Looking at quality rather than price? See the Stability AI score on APIbenchmarks. Full entry: Stability AI pricing.