AI book cover generator: a 1600×2560 Kindle ebook cover

To make a book cover with AI, generate the cover art at the store's size and set the title and author name yourself. For a Kindle ebook, Amazon KDP recommends 2,560 pixels tall by 1,600 wide, and on Sume, ChatGPT Image 2.5 takes exactly 1600 × 2560 as a custom size. A paperback needs a wrap-around cover with a spine and bleed, built on KDP's template in a layout tool.

KDP's numbers are quoted from its Help pages Cover Image Guidelines and Create a Paperback Cover, which can change; Sume facts come from the Image API docs and the Sume API reference. All were read on 2026-09-27.

What size is a Kindle ebook cover?

KDP's recommendation for the marketing cover image, the one shown on your book's Amazon detail page:

How do I generate an ebook cover with Sume?

Send POST /v1/images to ChatGPT Image 2.5 (openai/gpt-image-2.5) with image_size 1600 × 2560. Both edges are multiples of 16, and 4,096,000 pixels is inside the 655,360–8,294,400 range. Ask for jpeg, KDP's preferred format, and describe plain areas where the title and author name will go.

• To base the art on a character sketch or photo, add it in input_references as a public HTTPS URL; ChatGPT Image 2.5 takes up to 16. The model draws a new image, so check faces and details.
• Add n for up to 4 versions, the model's ceiling today; each image is billed. The price is estimated from size and quality, and usage.cost is the USD amount billed.
• Results are Sume-hosted, signed URLs in data[].url. Download the file and check it against KDP's 5 MB limit.
• KDP lists 300 DPI as a minimum. DPI is a label stored in the file rather than extra pixels, so set it when you export the final cover.

curl -X POST "https://api.sume.com/v1/images" \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-image-2.5",
    "prompt": "Book cover art for a mystery novel: a foggy harbor town at dusk, one lit window, muted blue palette, plain sky in the top third and a quiet band at the bottom for type, no text",
    "image_size": { "width": 1600, "height": 2560 },
    "output_format": "jpeg"
  }'

Should the AI write the title and author name?

KDP asks you to check the cover for typos and to make sure the title and author name match your Amazon detail page. Generated lettering can be misspelled, so the safer route is to set the words in a design tool on top of the art. If the model draws them, proofread every letter. AI image with text covers both routes.

Can I make a paperback cover this way?

Only the art. KDP wants a paperback cover as a single PDF that includes the back cover, spine, and front cover as one image, with 0.125 inch (3.2 mm) of bleed added to the top, bottom, and outside edges. Its cover calculator and template generator lays out the full cover from your ink and paper choices, trim size, and page count.

Sume's Image API returns PNG, JPEG, or WebP files, not a PDF, so place the generated art in KDP's template in a layout tool. KDP asks for images at a minimum of 300 DPI, so each printed inch of art needs 300 pixels; AI image for print works through the pixel math and upscaling.