Stability AI API pricing: credit costs and balance tracking

How the credit system and signup balance work

The platform uses a fixed prepaid ledger. One credit costs exactly $0.01. If a model generation costs 6.5 credits, you're paying $0.065 for that call.

When you register an account on the Stability AI API Platform, you get 25 free credits right away ($0.25 in value). That's enough to run three or four calls on the flagship image models or eight calls on lighter pipelines. Once those run out, you buy credits by logging into your account and heading to the Billing section. If you run high volumes, Stability AI offers custom enterprise pricing and bulk discounts through their sales team.

The Platform REST API expects multipart form POST requests authenticated by passing your secret key in an authorization header:

curl -X POST "https://api.stability.ai/v2beta/stable-image/generate/core" \
  -H "authorization: Bearer $STABILITY_API_KEY" \
  -H "accept: image/*" \
  -F prompt="A technical diagram on paper" \
  -F output_format="webp"

Requests consume credits immediately from your organization's pool. If your key leaks or your loop goes wild, it burns through whatever balance is sitting in your account until the balance hits zero.

Image generation costs by model

Base generation prices vary based on model parameter size and latency optimizations. If you migrated off the old Stable Diffusion 1.6 API (which was discontinued on July 24, 2025 alongside the Stable Video API), the legacy SDXL 1.0 base model keeps that same pricing structure, starting from 0.9 credits per image.

The current generation endpoints sit under the /v2beta/stable-image/generate/* path and run on the Stable Diffusion 3.5 architecture or proprietary variants:

• Stable Diffusion 3.5 Large: The 8 billion parameter base model costs 6.5 credits per call at POST https://api.stability.ai/v2beta/stable-image/generate/sd3.
• Stable Diffusion 3.5 Large Turbo: The fast variant of the Large model drops the cost down to 4 credits.
• Stable Diffusion 3.5 Medium: Covers the 2 and 2.5 billion parameter variants and costs 3.5 credits per image.
• Stable Diffusion 3.5 Flash: A distilled build of SD 3.5 Medium designed for high throughput, priced at 2.5 credits.
• Stable Image Ultra: The flagship service based on SD 3.5 Large costs 8 credits per generation at POST https://api.stability.ai/v2beta/stable-image/generate/ultra.
• Stable Image Core: Optimized for fast image output at 3 credits per generation at POST https://api.stability.ai/v2beta/stable-image/generate/core.

If you're comparing image providers, you might also want to look at our breakdown of Ideogram API pricing: what each image costs, how API credits and keys are billed and how to read usage and spend or our review of How does fal.ai pricing work? to see how third-party host rates line up.

Editing, upscaling, and 3D generation costs

Beyond raw image generation, Stability AI groups image manipulation endpoints under /v2beta/stable-image/{edit,upscale,control}/*.

Upscalers

The upscalers have the widest price range on the platform:

• Fast Upscaler: Costs 2 credits ($0.02) to scale up resolution 4x, supporting up to 4 megapixels.
• Conservative Upscaler: Costs 40 credits ($0.40) to upgrade a low-res image to 4k without reinterpreting the visual elements.
• Creative Upscaler: Costs 60 credits ($0.60) to push an image to 4k using prompt guidance to invent missing details. Run this in a bad loop and twenty requests will cost you $12.

Image editing and controls

Most editing tools sit at a flat 5 credits ($0.05). Erase Object, Inpaint, Remove Background, Search and Recolor, and Search and Replace all cost 5 credits each. Outpaint is slightly cheaper at 4 credits, while Replace Background & Relight costs 8 credits.

For guided generation under the control endpoints, Structure, Sketch, and Style Guide cost 5 credits each. Style Transfer runs higher at 8 credits per generation call.

3D assets

Turning 2D images into 3D files burns credits fast. Generating a 3D asset from a single 2D image using Stable Fast 3D costs 10 credits ($0.10). If you use Stable Point Aware 3D (SPAR3D) to edit or generate the structure of a 3D object from a single image, that costs 4 credits ($0.04).

Stable Audio endpoints and pricing differences

Audio pricing has two conflicting numbers across official Stability AI resources that you need to watch out for.

On the main pricing page (docs.stability.ai/pricing), Stable Audio 3.0 (which generates up to six minutes of audio) and Stable Audio 2.5 (which generates up to three minutes) are both listed at 8 credits ($0.08).

However, in the platform machine-readable specification (platform.stability.ai/llms.txt), the endpoints are listed at higher rates:

• POST https://api.stability.ai/v2beta/audio/stable-audio/text-to-audio is listed at 26 credits ($0.26). This is an asynchronous endpoint returning a 202 status with an {"id"}, which you then poll at GET /v2beta/audio/results/{id}.
• POST https://api.stability.ai/v2beta/audio/stable-audio-2/text-to-audio is listed at 20 credits ($0.20) and runs synchronously.

This higher pricing matches the August 1, 2025 pricing update, where Stability AI announced rate increases on select API services and priced Text to Audio and Audio to Audio at 20 credits. Budget for the higher 20 to 26 credit rate when calculating your client audio costs to avoid being surprised by your burn rate.

Why credits do not transfer between products

Stability AI sells credits across three separate products, and they do not pool together.

• Platform API: Credits bought in the Billing section of the API platform only work for API requests. They cannot be used in web interfaces.
• DreamStudio: Access is handled through a monthly subscription chosen inside the DreamStudio UI. When you upgrade a DreamStudio subscription, your used credits immediately reset to zero and your monthly allocation goes up. You can also buy separate Premium credits in the DreamStudio Billing section. Those Premium credits do not expire, and subscription credits are consumed first. None of these work on the API.
• Stable Assistant: Uses its own independent subscription model managed through the Manage Subscription page. Credits purchased here are completely exclusive to Stable Assistant and cannot be spent in DreamStudio or on the Platform API.

If your team uses both the API and consumer web tools, you have to fund each balance separately.

Balance monitoring, organizations, and runaway spend

Stability AI accounts can belong to multiple organizations. When you create an API key, that key is tied to your organization. Requests made using standard keys spend against your default organization's credit balance. If your application sends requests that explicitly select another organization, those calls draw down that secondary organization's credits instead.

The danger with raw API keys is that Stability AI keys don't just inspect usage; they can generate images and burn credits directly. If a developer accidentally commits a key or an asynchronous worker enters an infinite retry loop on a 60-credit Creative Upscaler job, the platform will silently burn credits until the organization runs completely dry. Stability AI does not offer an automated killswitch on the key itself. If you suspect an unauthorized leak, your only immediate fix is to log into the platform dashboard, navigate to the API Keys page, and manually delete the compromised key.

This is where automated tracking helps. You can read our broader guide on How do I monitor spend across OpenAI, Anthropic, Gemini and other AI APIs in one place? to see how multi-provider tracking works.

Costbrake monitors your Stability AI account by reading the credit balance of your default organization on a regular schedule. Since 1 credit equals $0.01, spend is calculated directly from the balance drop between checks.

Checks run hourly on the Free plan, every 5 minutes on Pro and Team, and scale up to every 2 minutes during an active spike. If usage surges - defined as an hour that costs more than three times your 7-day hourly baseline and adds at least $5 more than usual - Costbrake fires a spike alert. It also alerts at 50%, 80%, and 100% of your set budgets, forecasts month-end overages based on your last 72 hours, and flags any new service showing up above $1.

Alerts go to email on the Free plan, with Slack, Discord, and signed webhooks available on Pro, and PagerDuty on Team. Costbrake has an opt-in killswitch feature called brakes for many cloud and AI platforms, though there are no brakes available for Stability AI yet (you still delete the key manually on their dashboard).

All stored credentials are encrypted with AES-256-GCM. You can connect Stability AI by hand in the web app, or point an assistant to our agent setup page, which gives your agent a temporary session that expires after one hour and cannot touch billing. Paid plans are flat-rate without taking a cut of your spend: Pro is $12 a month ($120 a year) and Team is $39 a month ($390 a year), and both start with a 14-day Pro trial with no credit card required. Check out Costbrake pricing for full feature limits.