Cover Design Specs: Bleed, DPI, Spine & Trim

A beautiful cover that's built to the wrong specifications will be rejected at upload or — worse — print with a crooked spine and clipped text. Here's the technical side of cover files, so your design survives the journey from screen to shelf.

1. eBook covers: pixels and aspect ratio

The eBook cover is a single front-only RGB image. Retailers want a tall portrait aspect ratio of roughly 1.6:1 (height:width). A reliable target is 2,560 × 1,600 px, saved as a high-quality JPEG in the sRGB color space. Design for the thumbnail first: most readers see your cover at the size of a postage stamp, so the title must be legible and the focal point clear when scaled down.

2. Print covers: think in inches, design in CMYK

A print cover is a single flat spread — back cover, spine, and front cover — sized to your book's exact dimensions, in CMYK at 300 DPI. RGB files can shift color on press; converting to CMYK up front means the proof matches your screen far more closely.

The full-wrap math

The total cover width is not just two covers side by side — you must add the spine and bleed:

Total width  = bleed + back trim + spine + front trim + bleed
Total height = bleed + trim height + bleed

Standard bleed is 0.125 in on every outside edge (so artwork runs past the cut line and never leaves a white sliver). The spine width depends on page count and paper:

Spine width (in) = page count × paper thickness (PPI factor)
e.g. 300 pages × 0.0025 in ≈ 0.75 in spine

3. Safe zones, spine text, and the barcode

• Safe zone: keep title, author name, and key elements at least ~0.25 in inside the trim so nothing important is cut.
• Spine text: only add spine text above a minimum page count (around 100+ pages); below that, the spine is too thin and the printer may reject it. Center text and leave a safe margin so a slight bind shift doesn't clip letters.
• Barcode: print-on-demand services usually place the ISBN barcode automatically in the lower-right of the back cover — leave a clear, light area roughly 2"×1.2" there so it stays scannable.

Design for the thumbnail; build for the printer. A cover has to win attention and survive production.

4. Typography and contrast that survive scaling

Genre signaling lives largely in type and color. Use high contrast between title and background, limit yourself to one or two type families, and avoid thin hairlines that vanish at thumbnail size or break up in print. Test your cover at 150 px tall on a white and a dark background — if the title is still instantly readable, it will perform in a store grid.

5. Deliverables checklist

• eBook JPEG (2560×1600, sRGB)
• Print full-wrap PDF/X-1a (CMYK, 300 DPI, correct spine, bleed, fonts embedded)
• Layered source file for future edits
• 3D mockups (PNG with transparency) for marketing