Audiobook is the fastest-growing book format, and every audiobook needs its own cover. The mistake most authors make is treating the audiobook cover as an afterthought, cramming their rectangular book cover into a square and calling it done. That approach produces covers that look unprofessional and fail to convert browsers into listeners. Here is how to do it right with AI.
ACX and Audible Cover Specifications
| Spec | Requirement |
|---|---|
| Dimensions | 3200 x 3200 pixels (square) |
| Minimum size | 2400 x 2400 pixels |
| File format | JPEG or PNG |
| Color space | RGB |
| Max file size | Under 2 MB (JPEG) |
| Content | Must include title and author name. No pricing, URLs, or "audiobook" text. |
Findaway Voices, Authors Republic, and other audiobook distributors use the same 3200 x 3200 standard. One square file works across all audiobook platforms.
Why Your Book Cover Does Not Work as an Audiobook Cover
A standard ebook cover is 2560 x 1600 pixels, a tall rectangle with a 1.6:1 ratio. An audiobook cover is a perfect square. These are fundamentally different canvases, and treating them the same produces bad results.
What goes wrong:
- Cropping kills the composition. Cutting the top and bottom off a rectangular cover to make it square removes roughly 40% of the artwork. If your cover has a character's face at the top and title at the bottom, you lose one or both.
- Squishing distorts everything. Compressing a tall image into a square stretches everything horizontally. Faces look wrong. Text looks wrong. Everything looks wrong.
- Pillarboxing looks amateur. Adding black bars on the sides of a rectangular cover to fill a square canvas screams "I did not make a real audiobook cover."
- Text is too small. Typography sized for a tall rectangle becomes tiny and unreadable when the image is displayed at audiobook thumbnail sizes.
How to Adapt an AI Book Cover to Square Format
The right approach is to treat the audiobook cover as a related but separate design. Keep the same visual identity (colors, style, imagery) but compose it for a square canvas.
Regenerate at 1:1 aspect ratio
Go back to your AI tool and generate a new version of your cover concept at a 1:1 (square) aspect ratio. Use similar prompts to your original cover but adjusted for the square canvas. In Midjourney, use --ar 1:1. This produces a native square composition rather than a forced crop.
Upscale to 3200 x 3200
Most AI tools output 1024 x 1024 for square images. Upscale using Upscayl (free) or Topaz Gigapixel to reach at least 3200 x 3200 pixels. A 4x upscale from 1024 gives you 4096 x 4096, which you can then crop down.
Add large, bold typography
Audiobook title text needs to be significantly larger than ebook cover text. The title should occupy at least 30-40% of the cover area. Use high-contrast colors and bold weights. Test readability at 150 x 150 pixels before finalizing. The Art Director Method includes audiobook-specific typography sizing guidelines.
Export and test
Export as a high-quality JPEG under 2 MB, RGB color space. Before uploading, shrink your design to 150 x 150 pixels on screen and check: can you read the title? Can you identify the genre at a glance? If not, simplify further.
Text Readability at Small Sizes
Audiobook covers appear at multiple sizes across platforms, and the smallest sizes are where most browsing happens.
Display Sizes in the Wild:
- 150 x 150 px - Search results and recommendation carousels on Audible
- 300 x 300 px - Browse pages and category listings
- 500 x 500 px - Product detail page on mobile
- 3200 x 3200 px - Full size (only seen when zooming in on desktop)
Typography Rules for Audiobook Covers:
- Title: Large, bold, high contrast. Minimum 30% of cover height. Sans-serif or heavy serif fonts.
- Author name: Clearly visible but secondary to title. At least 15% of cover height.
- Subtitle: Omit entirely. There is not enough space at thumbnail sizes.
- Series name: Only if it fits. Keep it very small or include it in the title area.
- Contrast: White text on dark backgrounds or dark text on light backgrounds. No mid-tone text on mid-tone backgrounds.
Frequently Asked Questions
ACX and Audible require audiobook covers to be exactly 3200 x 3200 pixels, square format. The file must be JPEG or PNG, RGB color space, with a minimum of 72 DPI. Findaway Voices and other distributors also use 3200 x 3200 as their standard.
You should not simply crop or squish your ebook cover into a square. Ebook covers are tall rectangles (1.6:1 ratio), and forcing them into a square either cuts off major portions of the art or leaves awkward blank space. The better approach is to redesign the composition for square format, keeping the same visual identity but rearranging elements for the new shape.
Audiobook covers are displayed as square thumbnails in the Audible app, Apple Books, and audio player widgets. The square format matches how audio content is displayed across all platforms. It is the universal standard for audio media artwork, just as album art has been square since the LP era.
Use large, bold, high-contrast fonts. The title should fill at least 30-40% of the cover height. Limit text to title and author name only. No subtitles, taglines, or review quotes. Test your design by viewing it at 150 x 150 pixels on screen. If you cannot read the title at that size, increase the font size or simplify the layout.
The top mistakes are: using a rectangular book cover without adapting it to square format, text that is too small to read at thumbnail size, too many design elements competing for attention in a small space, low contrast between text and background, and not testing the design at actual display sizes used by Audible and other platforms.
Related Guides
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The Art Director Method covers every format, including audiobook-specific design strategies, AI prompt adjustments for square compositions, and typography sizing that works at thumbnail scale.
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