How eBook cover size is specified
Retailers specify covers in pixels, not inches, because eBooks are rendered on screens. The numbers matter in two ways: the total pixels set the sharpness on high-density displays, and the ratio sets whether the image fills the frame without bars.
The ideal KDP cover is 1600 pixels wide by 2560 pixels tall, a 1.6 height-to-width ratio, at about 4.1 megapixels. The absolute minimum KDP will accept is 1000 by 1600, or 1.6 megapixels, but that minimum looks soft on modern phones and tablets. Apple Books prefers 1400 by 2100 at 1.5, with 1400 as the shortest-side minimum. Kobo and Google Play both list 1600 by 2400 at 1.5 as their recommended, with Kobo enforcing a 5 MB file cap and Google allowing 50 MB. IngramSpark asks for 1800 by 2700 at 1.5 and 300 DPI, also under 50 MB. Barnes & Noble Press mirrors the 1600 by 2400 at 1.5 with a 20 MB cap. The tool reports the recommended, the minimum, the ratio, and the file limit for the retailer you select, so you can see the tradeoffs without hunting five help centers.
DPI is often mentioned alongside these numbers, but for eBooks it is shorthand for detail rather than a print instruction. A 1600 by 2560 file contains the same detail whether it is tagged 72 DPI or 300 DPI; the tag does not add pixels. Export at the pixel size the retailer asks for and think of 300 DPI as a reminder to export at print-quality sharpness at those pixels, not as a separate setting. Do not upscale a small file to fake a larger one; upscaling invents pixels without inventing detail and produces a soft cover that still fails the sharpness test.
File format matters because the retailer will re-encode. All major retailers accept baseline JPEG in sRGB and most also accept TIFF, but JPEG is the practical delivery for every store. Avoid progressive JPEG, which some pipelines handle poorly; use baseline optimized at quality 90 to 95. A 1600 by 2560 sRGB JPEG at that quality is typically 2 to 5 MB, well under the lowest cap. A TIFF at the same pixels is 12 MB and offers no visible advantage on screen. Save JPEG, keep the Photoshop or Affinity master as a layered file, and keep the JPEG under the smallest limit you publish to so the same file passes everywhere.
Amazon KDP: the default that sets the ceiling
KDP lists the ideal as 2560 pixels on the long side, which for a portrait cover is 1600 wide by 2560 tall. The ratio is 1:1.6, meaning height is 1.6 times width. The minimum is 1000 by 1600. The maximum file size is 50 MB. The color profile should be sRGB; Adobe RGB or CMYK will shift on upload because the pipeline converts to sRGB for display and then re-encodes.
The larger ideal matters because KDP shows the cover at many sizes, not just thumbnail. The product page hero may be 400 to 600 pixels wide, but the Look Inside and the Kindle device libraries show the cover smaller. A 1600 by 2560 master downscales cleanly to all of them. A 1000 by 1600 master downscales to a soft hero and a very soft thumbnail. The 4-megapixel file also future-proofs the listing; the minimum has not changed in years while device density has. Export at the ideal even though the uploader accepts the minimum.
Keep the ratio exact. Do not add bars or letterboxing to force a different ratio into 1.6. Do not build a 1.5 cover and place it on a 1.6 canvas with white bars to pad it; KDP will display the bars as part of the cover and the effective image will be smaller. Build at 1600 by 2560 and keep all type and key art inside a 5% inset from the edge, because some storefronts crop a pixel and some add a hairline keyline.
Apple Books, Kobo, Google Play, and the 1.5 world
Apple Books prefers 1400 by 2100 at 1:1.5, with 1400 as the minimum on the shortest side. The ratio is slightly squatter than KDP's 1.6, so a KDP cover at 1600 by 2560 is taller and will be pillarboxed with tiny vertical bars on Apple if you reuse the same file without re-cropping. The bars are subtle, but the cover is effectively smaller. If Apple is a primary retailer, export a separate 1400 by 2100 master at 1.5 with the same art repositioned, rather than letting the store pad the image.
Kobo lists 1600 by 2400 at 1.5 as recommended, with 800 by 1200 as the minimum, and enforces a 5 MB file cap. That cap is the tightest among the majors. A 1600 by 2400 JPEG at quality 95 is often under 4 MB, so the cap is not a problem unless the cover was saved at 100 quality with extra metadata. Strip metadata and keep the file under 5 MB so the same JPEG passes Kobo and also passes the 50 MB stores without a second export.
Google Play Books also lists 1600 by 2400 at 1.5 with a 1000 by 1500 minimum and a 50 MB cap. In practice Google re-encodes aggressively, so a sharp master at 1600 by 2400 survives the store's compression better than a 1000-pixel master. The same file you send to Kobo will pass Google if it is under 5 MB, but you can also send the Kobo file and keep a larger KDP file separate.
IngramSpark asks for 1800 by 2700 at 1.5 and 300 DPI, under 50 MB. The pixel count is higher than the other 1.5 retailers, which makes it a good master for downscaling: a 1800 by 2700 master downscaled to 1600 by 2400 for Kobo or Google retains detail, while upscaling a 1400 by 2100 file to 1800 by 2700 softens. If you publish wide including IngramSpark, export at 1800 by 2700 and derive the smaller sizes from it, rather than exporting at 1400 and upscaling for the larger.
Barnes & Noble Press mirrors the 1600 by 2400 at 1.5 with a 20 MB cap and a 1000 by 1600 minimum. The numbers are compatible with the Kobo/Google set, so one 1600 by 2400 file covers three retailers, while KDP wants the taller 1.6 and Apple wants its own 1400 by 2100.
Ratio, letterboxing, and why it matters more than pixels
A one-pixel error in width is invisible. A ratio error is visible. A 1.5 cover placed in a 1.6 frame will show thin vertical bars at top and bottom or will be cropped. A 1.6 cover placed in a 1.5 frame will show side bars or will have its top and bottom clipped. The bars are small — a few pixels — but the cover looks slightly smaller and less confident next to correctly ratioed comps.
The difference between 1.5 and 1.6 is three percent in height for the same width. At 1600 wide, 1.5 is 2400 tall and 1.6 is 2560 tall, a 160-pixel difference. That is not a rounding error; it is a visible composition shift if the title sits near the top or bottom. A title that sits 100 pixels from the top at 1.6 will sit 20 pixels closer to the edge at 1.5 after cropping. The fix is not to fudge the ratio in the tool. The fix is to build at the ratio the retailer asks for and keep critical type at least 5% inside the edge, so a small crop does not clip.
If you must ship one file everywhere, choose 1.5 as the common ratio. It is the majority among the wide retailers, and KDP's handling of a 1.5 file is to add tiny horizontal bars rather than to crop. The bars are less damaging than a 1.6 file pillarboxed on every other store. Better still, export both ratios from the master: a 1600 by 2560 for KDP and a 1600 by 2400 for the 1.5 stores. The layered master makes the second export a one-minute re-crop.
DPI, compression, and color that survive the pipeline
Every retailer re-encodes the cover you upload. The pipeline converts to sRGB, strips most metadata, normalizes orientation, and recompresses at a quality it chooses. The goal is to give the pipeline a file that survives that sequence without visible loss.
Export at the exact pixels the retailer lists, in sRGB, as a baseline JPEG at quality 90 to 95. Quality 90 is visually identical to 100 at a fraction of the size and compresses better without blocking. Quality 100 creates a larger file that the retailer's own recompression then degrades more aggressively. Progressive JPEG saves no visible quality for covers and can produce decoding artifacts on some readers; use baseline optimized.
Keep the file well under the smallest cap you publish to. A 1600 by 2560 at quality 92 is typically 2.5 to 4 MB. At quality 97 it may be 6 to 8 MB, still under 50 MB for KDP but over 5 MB for Kobo. The extra quality is not visible at thumbnail size; the extra bytes are. Aim for quality that keeps the largest spec under 5 MB so one file passes all stores, or keep two files where the Kobo variant is more compressed.
Color profile is sRGB. If your master is in Adobe RGB or Display P3, convert to sRGB on export and preview the conversion. Saturated reds and oranges shift most. A cover that looks rich in P3 may look duller in sRGB unless you adjust. Do not upload CMYK; the store will convert it and the shift is less predictable.
Sharpen for screen after resizing. A cover downscaled from a 6000-pixel master to 2560 needs a light unsharp mask; a cover upscaled from 1200 to 2560 needs more aggressive sharpening that still will not rescue softness. The sharpest workflow is to keep the layered master at 4000 to 6000 pixels on the long side and export down to each retailer's size with a light sharpen, rather than designing at 1600 and having nowhere to go when the retailer asks for larger.
Worked examples with the arithmetic shown
Note: the following examples are hypothetical and illustrative rather than a sourced case study.
A KDP-only author who wants the simplest workflow exports one file at 1600 by 2560, 1.6, sRGB JPEG baseline at quality 92, about 3.5 MB. The breakdown shows width 1600, height 2560, ratio 1:1.6, megapixels 4.1, minimum 1000 by 1600, format JPEG, max 50 MB. The recommendation notes that 2560 tall is ideal even though 1000 tall is the minimum, and that the ratio must stay exact without bars. This single file will pass KDP and will also pass the wide stores if the author later expands, with only the ratio causing tiny bars on the 1.5 stores.
An author publishing wide across KDP, Apple, and Kobo needs two ratios. She exports a 1600 by 2560 at 1.6 for KDP and a 1600 by 2400 at 1.5 for Kobo and Google Play, and a 1400 by 2100 at 1.5 for Apple derived from the same master. The KDP file is 4.1 MP, the Kobo/Google file is 3.84 MP, and the Apple file is 2.94 MP. All three are under 5 MB at quality 92, so the same JPEGs pass the strictest cap. The table in the output shows all six retailers at a glance with the selected row marked, so she can see that a 1.6 file reused on Apple would be pillarboxed with about 80 pixels of bar on each side of the height.
An author with an existing 1200 by 1800 cover from an old template tests whether the file can be reused. The tool shows that 1200 by 1800 at 1.5 is below the KDP recommended of 1600 by 2560 and below the Apple recommended of 1400 by 2100. The arithmetic says the file is 2.16 MP versus the 4.1 MP KDP wants, or about half the detail. Upscaling to 1600 by 2560 would invent pixels without adding detail, and the cover will look soft next to native 2560 comps. The correct move is to re-export from the layered master at 2560 tall with a light sharpen, not to upscale the old JPEG.
A Kobo-focused author who built a 2000 by 3000 cover at 1.5 tests the file limit. The breakdown shows 6.0 MP, ratio 1.5, minimum 800 by 1200, and file size at quality 95 may be 6 to 7 MB, over Kobo's 5 MB cap. The fix is to keep the same pixels but lower quality to 90, which typically brings the file under 5 MB with no visible loss at thumbnail size. The tool reports the cap so the author knows the failure mode is file size, not pixels.
Edge cases and format specifics
Square or near-square art does not belong on an eBook cover. Retailers will not accept a 2000 by 2000 eBook cover as the primary image, even though the file is technically large enough, because the ratio is wrong. If the art is square, extend the canvas to the required ratio with a color or texture that matches the design, rather than stretching the art. Stretching changes the art's proportions and is immediately obvious.
Landscape covers are similarly rejected. An eBook cover must be portrait. A landscape photograph must be cropped or placed on a portrait canvas, not rotated. The product page hero is portrait, the thumbnail is portrait, and the device libraries are portrait; a landscape file will be letterboxed with large bars and the art will be small.
Series uniformity can conflict with per-retailer ratios if the series was built at one ratio and the next retailer wants another. Keep the series master at the largest ratio you will need — typically 1.6 — and re-crop for 1.5 by trimming a small strip from top and bottom rather than by scaling width. Scaling width changes stroke weight; trimming preserves it. Keep the title inside the safe 5% inset so a small trim does not clip.
Audiobook covers are not eBook covers. ACX and Findaway require 3000 by 3000 square at 1:1, while eBook retailers require portrait. Do not reuse the eBook portrait as the audio square, or vice versa, by stretching. Build a separate square master for audio from the same art, centered, with the title re-set for the square rather than auto-cropped.
Print covers are not eBook covers. A print wrap includes spine and bleed and must be uploaded as a separate PDF or spread. The eBook cover is a single front-panel JPEG at the portrait ratio. Do not export the print spread and crop it to the eBook ratio; the spine and bleed will disturb the composition. Build the eBook front panel from the layered master at the portrait pixels.
How to test the cover for real
Export the file at the exact pixels the tool reports for that retailer, then open it at 100% in a viewer that does not smooth. At 1600 by 2560, the image is larger than most displays, so 100% will be bigger than the product page. Zoom to the size the store actually shows — roughly 400 to 600 pixels tall on the product page hero and 160 pixels wide in search — and see whether the title reads without leaning in. Then upload to the retailer's previewer: KDP has a cover preview, Apple has Apple Books for Authors preview, and Google has a preview in the Books upload flow. The preview shows the re-encoded result, which is the ground truth.
Test on a phone. Open the live listing in an incognito window after publication and view the search result grid at default zoom, then as a customer who searches a category that surfaces your ASIN or a close comp. The thumbnail on a phone at arm's length is the smallest context the cover must survive. If the title reads there, it reads everywhere it matters. If it does not, the fix is not more pixels but higher contrast, heavier weight, or a cleaner background behind the letters, as the thumbnail legibility tool measures.
Test the file size as well as the pixels. A file that is exactly the right pixels but 7 MB will pass KDP and fail Kobo. The tool reports the max size per retailer precisely for that reason. Check the exported JPEG's byte size in the file manager before upload, not just the pixel dimensions in the design tool.
Common mistakes and how to avoid them
Exporting at the minimum rather than the recommended is the most common. The uploader accepts 1000 by 1600, but the product page and the thumbnail are built from that minimum, so the cover is soft next to comps that exported at 2560. Export at the recommended every time; the minimum is a floor, not a target.
Adding bleed to an eBook cover is the second. Bleed is for print wrap covers where the trimmer removes excess. eBook covers are displayed edge to edge without trim, so the file should be exactly the pixel dimensions without extra bleed edges. A 1600 by 2560 eBook cover with an added 0.125-inch bleed built at pixels will be the wrong ratio and will be padded with bars.
Uploading in the wrong color profile is the third. A cover saved as CMYK or Display P3 will be converted to sRGB by the pipeline, and the conversion shifts saturated colors. Convert to sRGB on export and preview the conversion. The shift is most visible in reds and oranges, which often look duller after conversion unless adjusted.
Saving as PNG when JPEG is expected is the fourth. PNG at 1600 by 2560 is 8 to 12 MB without visible advantage; some retailers re-encode PNG more heavily than JPEG and the result can look softer. Save JPEG baseline at quality 90 to 95 and keep the PNG master only as an archival layered file.
Stretching the cover to fit the ratio is the fifth. A 1.5 master stretched to 1.6 changes letterforms; tall letters become taller and narrow letters become narrower, and the title that looked confident now looks condensed. Re-crop from the layered master at the correct ratio rather than transforming the flat JPEG.
Forgetting to strip metadata is the sixth. A JPEG that carries a large embedded preview or an ICC profile mismatch can add megabytes without adding detail. Strip extraneous metadata on export and keep the file under the smallest cap you publish to so one file passes everywhere. The tool reports the cap so you know which retailer is the constraint.
Choosing the right export when you publish wide
If you publish KDP-only, export one file at 1600 by 2560, sRGB baseline JPEG, quality 90 to 95, under 5 MB for safety. That single file is the correct KDP master and will also pass the wide stores if you later expand, with only tiny ratio bars on the 1.5 stores.
If you publish wide from the start, export two masters from the same layered file: a 1600 by 2560 at 1.6 for KDP and a 1600 by 2400 at 1.5 for Kobo, Google, and IngramSpark, and derive the Apple 1400 by 2100 from the 1.5 master. The layered master at 4000 to 6000 on the long side makes both exports sharp with a light sharpen after downscaling, rather than designing at 1600 and upscaling when the larger is needed.
If you already have a catalog of covers at the old minimums, do not batch-upscale them. Re-export from the layered masters at the current recommended pixels with a light unsharp mask. The recompression will look sharper than an upscaled JPEG, and the new files will be under the caps without stripping visible detail.
Final checks before you commit and upload
Run the tool once with the retailer you actually publish to and once with a wide case where the ratio is opposite. If the same file must serve both, see whether the bars are acceptable or whether a second ratio is worth the one-minute re-crop. If the bars would intrude on the title, build both.
Open the exported JPEG at the exact pixels and measure the title's distance from the edge. It should be at least 5% inside the frame on all sides, so a small crop or keyline does not clip. Do not add bleed to an eBook cover; keep the file at the exact pixels without extra edges.
Check the byte size. A 1600 by 2560 at quality 92 should be well under 5 MB; at quality 98 it may exceed Kobo's cap. Lower quality to 90 and re-export rather than resizing pixels down, because pixels determine sharpness and quality determines file size more than the last 100 pixels do.
Upload and verify live. In the retailer's previewer, confirm the cover fills the frame without bars or softness. On a phone listing in an incognito window, confirm the thumbnail reads at arm's length. If it does, lock the export settings — pixels, ratio, profile, quality, and file size — alongside the KDP file name. When the next book grows, reuse the same settings rather than relying on memory that the last cover was 1600 by something. The numbers are fixed; your file is the variable.