How to Format Images in eBooks: Sizing, Placement & Captions (2026)

A photograph that looks perfect in your Word manuscript can turn into a blurry smudge or a broken grey box the moment it reaches a Kindle. Images are the most common source of formatting trouble in eBooks — not because authors choose bad photos, but because an eBook is not a print book, and every rule you know about resolution and sizing works differently on a screen that reflows. New to Kindle publishing? Start with our complete Kindle eBook formatting guide for authors, then come back for the image details.

This 2026 guide covers the right pixel dimensions, why DPI barely matters on screens, JPEG versus PNG, placement options, captions and alt text, and how images behave on Kindle, Apple Books, and Kobo.

Why eBook Images Break

The root problem is a mismatch of mediums. A print book is fixed: every page has exact dimensions. An eBook is fluid. Readers control the font size, margins, and orientation, and the text reflows around your image every time any of those change. Formatting images for eBooks means managing that collision gracefully.

Devices make it worse. A photo that fills a phone screen looks like a postage stamp on a desktop monitor, and full color on a tablet becomes grey on an e-ink Kindle. Amazon’s publishing guidelines expect authors to test across this variety, which is why the free Kindle Previewer exists. Use it before you publish, every time.

The third cause is Word. Authors insert images at huge original dimensions with floating text wrapping, and those settings translate badly to EPUB or Kindle format: images lock to absolute positions, scale to fixed pixel widths, or balloon the file size. Amazon charges a delivery fee of $0.15 per megabyte for eBooks in the 70 percent royalty tier, so 8-megabyte camera photos quietly eat your royalties.

Resolution and DPI: What Matters on Screen

Unlearn this myth first: DPI means almost nothing for eBooks. DPI is print metadata that tells a printer how densely to pack pixels onto paper. Screens ignore it and read the image’s pixel dimensions. A 2400-pixel-wide photo and a 400-pixel-wide photo are completely different objects to an e-reader, whether both claim to be 300 DPI or 72 DPI.

Amazon’s Kindle Publishing Guidelines do say “300 ppi for the intended display size,” which confuses people. What it really means: multiply the physical display size by 300 to get your minimum pixel count. Amazon defines a full-page image as a 4-by-6-inch area after margins — so the minimum is 1200 by 1800 pixels. That is the only DPI number worth remembering, and it is really a pixel-dimension number in disguise.

The practical rules follow. Never upscale a small image — stretching 600 pixels into 1800 adds fuzz, not detail. For full-page or hero images, use at least 1200 pixels on the shortest side; 1500 to 2000 on the longest side is comfortable. Small inline graphics need only 200 to 400 pixels. And save everything in RGB: Kindle renders CMYK incorrectly.

JPEG vs PNG: Picking the Right Format

Kindle supports JPEG and PNG for interiors, and the choice is mostly about image type. Photos — continuous-tone images with gradients and shadows — should be JPEG. It compresses photographic data efficiently, and at quality 75 to 85 the image looks crisp at a reasonable file size. Amazon’s guidelines set a floor of quality 40, but treat that as a floor, not a target.

Line art, charts, diagrams, screenshots, and anything containing text should be PNG. PNG is lossless, so sharp edges stay sharp — text in a JPEG can develop a fuzzy compression halo, which is exactly what you do not want in a diagram with small labels. PNG files are larger, but diagrams are usually small in pixels, so totals stay manageable.

Three exceptions matter. First, Kindle does not support transparency: transparent PNG backgrounds can render as black boxes, so flatten them onto white first. Second, TIFF and BMP are unsupported for interiors. Third, SVG support on Kindle is only partial and inconsistent; export vector artwork as high-resolution PNG and test it in Kindle Previewer.

Sizing Your Images

The most important sizing rule comes from Amazon itself: never size images with fixed pixel or point values. Use percentages for widths and ems for heights. A fixed pixel width that looks perfect on a phone is comically small on a desktop app and oversized on an old e-ink reader. Percentages scale with the screen; pixels do not.

For a standard block image — on its own line, which is what most of your images should be — Amazon’s recommended CSS is simple: display the image as a block element, set width to 100 percent, and set object-fit to contain. The image fills the available width while keeping its aspect ratio. This is the default, safest choice for chapter photos.

Full-width images suit chapter-opening artwork and wide landscapes, under the same width-100-percent rule. But note that a landscape photo on a portrait phone screen renders small — it can only be as tall as its aspect ratio allows. If a photo’s detail matters, crop it to portrait or square so it renders larger. A full-page image ratio around 9:11 uses screen space well.

For text-wrapped images — a small portrait floating left with text beside it — Amazon’s examples use float widths around 20 percent. Keep them small and add margins so text never butts against the image. Wrapping is unreliable across reading apps, though; some devices stack instead of wrap. Never put essential information in a wrapped position — when in doubt, use a block image.

Inline images — tiny graphics inside a line of text, like a star icon — should be sized in ems, roughly 1 em tall, aligned to the baseline. Export these as lossless PNGs, and add max-width: 100% to your stylesheet so nothing overflows the reading area.

Inline, Full-Width, or Full-Page: Placement

Placement matches the image’s job to the right layout. Inline, full-width, and full-page each suit different content, and mixing them deliberately is what makes an illustrated eBook feel professionally designed.

Inline placement is for images inside the reading flow: a small author photo, an icon beside a tip, a map marker. Keep them small, give them alt text, and do not make them a focal point. Inline images rarely cause problems because they move with the text.

Full-width images break the flow on purpose. They span the text column on their own line: a landscape photo opening a travel chapter, a wide diagram after it is first discussed. The key rule is that the image gets its own paragraph — never paste a full-width image mid-paragraph in Word, or the conversion may anchor it oddly.

Full-page placement is for images that deserve the whole screen: maps, detailed charts, photo spreads. Give the image a dedicated page — a page break before and after — so it renders as large as possible. Here is the truth about full-bleed: true edge-to-edge bleed only works reliably in fixed-layout eBooks. In reflowable books — what most authors publish — a full-width block image on a dedicated page is the closest you can get, and it looks great everywhere. If your book truly needs edge-to-edge imagery, like a children’s picture book, that is a fixed-layout book. Our comparison of fixed-layout versus reflowable eBooks walks through exactly when each is the right call.

Anchor images to text, not positions: in Word, set images to “in line with text” before conversion. Floating images are the number-one cause of images drifting to the wrong page or vanishing on Kindle.

Captions and Alt Text

Captions and alt text are different tools for different jobs, and professional eBooks need both. A caption is visible text beneath the image. Alt text is invisible metadata on the image tag, read aloud by screen readers. Skipping them is the most common amateur signal in otherwise well-formatted eBooks.

In EPUB 3, use the figure and figcaption elements: image and caption wrapped together so they travel as a unit when text reflows. A caption typed as a separate paragraph can end up orphaned on a different screen. Style captions subtly — slightly smaller than body text, often italic — and number figures sequentially if the book references them (“see Figure 4”).

Amazon’s rule for alt text: describe the image and its meaning in fewer than 140 characters. “Map of the 1849 gold rush trail from Missouri to Sacramento” is good; “image” is not. Decorative images get an empty alt attribute so screen readers skip them.

Kindle vs Apple Books vs Kobo

The same image file behaves slightly differently per platform. An EPUB 3 file with JPEG and PNG images, RGB color, sensible pixel dimensions, and alt text works everywhere — the differences are at the edges.

Kindle is the strictest. It supports JPEG and PNG but not TIFF, multi-frame GIFs, or transparency. Older e-ink devices convert everything to grayscale, so verify photos and charts stay readable without color. Kindle also downsamples oversized images during conversion — a 6000-pixel upload buys no extra quality, just a bigger file that Amazon shrinks anyway while charging you the delivery fee for the larger original.

Apple Books is the most standards-strict. It accepts EPUB only, validates rigorously, and rejects malformed files Kindle would silently accept. Apple has historically limited in-book images to about 3.2 megapixels per image, so keeping images under roughly 2000 pixels on the longest side stays comfortably inside the limit. Apple handles PNG transparency properly — but since the Kindle version needs flattened images anyway, flatten once and use the same files everywhere.

Kobo sits between the two: EPUB-based and tolerant of JPEG and PNG, with fewer documented quirks — images that validate cleanly work fine. Where Kobo differs most is the storefront, where covers drive browsing. And the format layer matters too: our EPUB versus MOBI versus PDF comparison covers how each format handles images.

Your Cover Image: The One File With Its Own Rules

The cover is technically an image inside your eBook, but it plays by storefront rules — and it is the only image where requirements differ sharply per platform. Get it wrong and the book can be rejected at upload.

Amazon KDP wants a portrait cover at 1600 by 2560 pixels, minimum 1000 by 625. The file must be JPEG or TIFF, in RGB, under 50 MB, with a height-to-width ratio of at least 1.6 to 1. The embedded cover inside the eBook file should be at least 1200 pixels in width or height. One design tip: very light covers can vanish against white store backgrounds, so add a thin medium-grey border around the edge.

Apple Books, Kobo, and Nook prefer a squatter ratio near 1.5 to 1. Apple wants a minimum of 1400 by 1873 pixels and prefers 1600 by 2400. Kobo recommends 1600 by 2400 in JPEG or PNG. Nook typically wants 1400 to 2000 pixels on the short side. Google Play Books aligns with 1600 by 2400. The table below puts the specs side by side.

The professional workflow is one master file, two crops: a single high-resolution master of 1600 by 2560 pixels or larger, then one crop at 1.6:1 for Amazon and one at 1.5:1 for everywhere else. Keep text and key artwork in the center safe zone, and never stretch a small image up to fit.

9 Image Mistakes That Make eBooks Look Amateur

Check your file against each of these real-world errors before you upload.

• Uploading camera-original photos at full size — an 8 MB photo adds delivery fees and gets downsampled by Amazon anyway.
• Saving everything as JPEG — diagrams and charts need PNG’s lossless sharpness, or labels go fuzzy.
• Leaving PNGs transparent — Kindle does not support transparency, so flatten backgrounds onto white.
• Using CMYK color mode — Kindle renders CMYK incorrectly; convert every image to RGB.
• Sizing with fixed pixels — a 500-pixel width suits one screen and fails on the rest; use percentages.
• Floating images in Word — “in front of text” anchoring drifts and overlaps on Kindle; use “in line with text.”
• Baking captions into images — text inside images is not searchable or accessible and blurs on scaling.
• Skipping alt text — Amazon calls for meaningful alt descriptions under 140 characters.
• Ignoring the grayscale check — e-ink Kindles show grey, so verify charts stay clear without color.

Conclusion: Images That Work on Every Device

The discipline comes down to a short list: think in pixels, not DPI; JPEG for photos and PNG for diagrams; RGB always; size with percentages; flatten transparency; caption with real text; describe with alt text; check in grayscale; and give the cover its own per-platform specs. Do that and your photos will look right on Kindle, iPhone, and Kobo alike.