# Steam capsule art with every size, the rules and an AI workflow

> The complete list of Steam store and library image sizes, what Valve allows on each, and a practical way to make all of them from your game's own characters.

- URL: https://www.summerengine.com/steam-capsule-art-generator
- Keyword: steam capsule art

**The short answer:** Steam needs a header capsule (920 x 430), small capsule (462 x 174), main capsule (1232 x 706), vertical capsule (748 x 896), at least five 1920 x 1080 screenshots, plus a library art set of a 600 x 900 capsule, 920 x 430 header, 3840 x 1240 hero and a transparent logo. With Summer you generate key art from your character and a reference image, then crop and export each size.

Capsule art is the first thing a Steam shopper sees, often at thumbnail size, in a grid next to games with professional art teams. It decides whether anyone clicks through to your trailer.

The rules are specific. Each asset has exact dimensions, most allow only your game's title as text, and the library hero allows no text at all. Getting one of them wrong means a rejected build review or a blurry crop on the store.

This page collects the current sizes from Steamworks documentation in one place and shows how to produce a consistent set with Summer's image models, starting from the characters that are already in your game.

## What it does

- **Key art from your own characters:** Use a screenshot or render of your hero as a reference image so the capsule matches the game, not a generic fantasy scene.
- **Wide and tall compositions:** Generate horizontal art for header and main capsules and vertical art for the vertical and library capsules.
- **Several image models:** Nano Banana 2 Lite, Seedream 5.0 Pro, GPT Image 2 and Grok Imagine 2 are available in Studio, so you can compare styles.
- **Transparent logos:** Background removal gives you a clean PNG logo for the library logo asset and for layering over art.
- **Exact crops by your agent:** From Claude Code, Cursor or Codex, the agent can crop and export every size locally with a script, checked against the table below.

## How it works

1. **Collect references:** Grab one or two clean shots of your main character and environment from the game.
2. **Generate the key art:** Prompt for the scene with the reference attached, once wide and once tall. Leave empty space where the logo will sit.
3. **Make the logo:** Generate or upload the title logo and remove the background for a transparent PNG.
4. **Compose and crop:** Place the logo on each composition and export every size in the table. Check the small capsule at 120 x 45 to make sure the title still reads.
5. **Disclose and upload:** Upload in Steamworks and disclose AI-generated art in the content survey.

## In Studio, or from the agent you already use

### In Summer Studio

Open the Image tab in Studio, pick a model, attach your reference image, choose a wide or tall aspect ratio and generate. Remove backgrounds for the logo, then download the images for layout and cropping.

[Open the Image tab in Studio](https://www.summerengine.com/studio?tab=image)

### From Claude, Cursor or Codex via MCP

Your agent calls summer_generate_image with your reference image, then crops and exports each Steam size on your machine and checks the dimensions. Summer does not have a one-click "all Steam sizes" preset yet; the agent does the layout work.

Example prompt for your agent:

```text
Use Summer to generate wide and tall key art of the knight from screenshots/hero.png standing on the cliff at sunset, leave room top center for the logo, then composite logo.png and export every Steam store and library capsule size into marketing/steam/.
```

[Set up the Summer MCP](https://www.summerengine.com/mcp)

## Steam store assets (required unless noted)

| Asset | Size (px) | Rules |
| --- | --- | --- |
| Header capsule | 920 x 430 | No quotes or other text beyond the game title |
| Small capsule | 462 x 174 | Logo must stay readable at the smallest size (Steam also generates 120 x 45 and 184 x 69) |
| Main capsule | 1232 x 706 | Logotype easily legible against the background |
| Vertical capsule | 748 x 896 | Same legibility rules as the other capsules |
| Screenshots | 1920 x 1080 minimum, 16:9 | At least 5 required |
| Page background (optional) | 1438 x 810 | Generated from your last screenshot if not provided |
| Bundle header (optional) | 707 x 232 | For bundle pages |

Sources: [Steamworks: store graphical assets](https://partner.steamgames.com/doc/store/assets/standard)

## Steam library assets (required)

| Asset | Size (px) | Rules |
| --- | --- | --- |
| Library capsule | 600 x 900 | No text beyond the game title; logo legible |
| Library header | 920 x 430 | No text beyond the game title; logo legible |
| Library hero | 3840 x 1240 | No text at all; keep key content inside the centered 860 x 380 safe area |
| Library logo | 1280 wide and/or 720 tall | Transparent PNG with only the logotype and optional logomark |

Sources: [Steamworks: library assets](https://partner.steamgames.com/doc/store/assets/libraryassets)

## What it costs

- Image, Nano Banana 2 Lite (1K): $0.04 (estimate)

Premium image models such as GPT Image 2 and Seedream 5.0 Pro cost more per image and show their price in Studio before you generate.

Prices are charged from your Summer usage balance. Generating assets needs a paid plan or a top-up: Pro is $20 a month and includes $20 of usage, and top-ups start at $5. The desktop engine itself is free to download.

## Prompts that work, and what comes back

Prompt patterns for key art. Attach a reference of your character to keep the art on model.

### Hero moment, wide

- Prompt: The knight from the reference image standing on a cliff at sunset, looking over a ruined city, dramatic rim light, painterly, empty sky top center for a logo, 16:9
- What you get: A horizontal composition for header and main capsules.

### Character portrait, tall

- Prompt: The same knight, three-quarter view, sword planted in the ground, glowing embers, dark background, vertical poster composition
- What you get: A vertical composition for the library and vertical capsules.

### Cozy game

- Prompt: The farmer character from the reference watering flowers in front of a small cottage, soft morning light, pastel palette, room for a title at the top
- What you get: Warm key art that reads well at thumbnail size.

### Library hero

- Prompt: Wide panoramic landscape of the game world with no characters and no text, key landmark centered
- What you get: A text-free background to crop to 3840 x 1240 with the landmark in the safe area.

[Guide to publishing a game on Steam](https://www.summerengine.com/blog/how-to-publish-game-on-steam)

## Steam's AI disclosure and capsule art

Steam's content survey asks you to disclose pre-generated AI content, defined as "any kind of content that ships with your game and is consumed by players that is created with the help of AI tools during development". Valve says it evaluates that content the same way as non-AI content, including checking that it matches your marketing. Store art that promises something the game does not contain is a problem whether a person or a model drew it.

The practical rule is to build capsule art from what is actually in your game. Using your own character renders as references keeps the art honest and consistent with your screenshots.

## Readability beats detail

Most people first see your capsule at a small size in a list. Test the small capsule at 120 x 45 and the header at half size. If the title does not read, simplify the background, enlarge the logo, or increase contrast before adding more detail.

- One focal character or object, not a crowd.
- Strong silhouette and contrast behind the logo.
- Consistent palette across every size so the set looks like one game.
- No review quotes, awards or sale text on capsules.

## Frequently asked questions

### What size is the Steam header capsule?

920 x 430 pixels. The library header uses the same size.

### What are the main and vertical capsule sizes?

The main capsule is 1232 x 706 pixels and the vertical capsule is 748 x 896 pixels.

### What size is the Steam library hero?

3840 x 1240 pixels with no text. Keep important content inside the centered 860 x 380 safe area.

### Can I put text on Steam capsules?

Only your game's title on the store and library capsules. No quotes or other strings. The library hero cannot include any text, and the library logo must contain only your logotype and optional logomark.

### Can I use AI-generated capsule art on Steam?

Steam asks you to disclose AI-generated content in the content survey, and reviews it like any other content. Base the art on what is really in your game.

### Does Summer make every size automatically?

Not with one click yet. Studio generates the key art and transparent logo; an AI coding agent using the Summer MCP can then crop and export every size from the table on your machine.

### Do I need to build my game in Summer to use this?

No. The image tools work for any game. Upload screenshots from your engine as references.

## Related tools and guides

- [Guide to publishing a game on Steam](https://www.summerengine.com/blog/how-to-publish-game-on-steam)
- [Steam game maker](https://www.summerengine.com/steam-game-maker)
- [AI game character generator](https://www.summerengine.com/ai-game-character-generator)
- [Summer for game marketers](https://www.summerengine.com/for/marketers)
- [Summer for indie developers](https://www.summerengine.com/for/indie-devs)
- [AI transparency on Summer](https://www.summerengine.com/ai-transparency)

## Sources

- [Steamworks: store graphical assets](https://partner.steamgames.com/doc/store/assets/standard)
- [Steamworks: library assets](https://partner.steamgames.com/doc/store/assets/libraryassets)
- [Steamworks: content survey (AI disclosure)](https://partner.steamgames.com/doc/gettingstarted/contentsurvey)

[Generate key art](https://www.summerengine.com/studio?tab=image)

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## Machine-readable resources

- Site index for agents: https://www.summerengine.com/llms.txt
- Full inlined content: https://www.summerengine.com/llms-full.txt
- Porting catalog: https://www.summerengine.com/llms-porting.txt
- Structured catalog: https://www.summerengine.com/agent-catalog.json
- Sitemap: https://www.summerengine.com/sitemap.xml
- Developer resources: https://www.summerengine.com/docs
- Summer API (assets from any agent or code; public per-call model prices): https://docs.summerengine.com/api