What DPI Should Interior Book Images Be for Print-on-Demand?

What DPI should interior book images be for print-on-demand? The short answer is 300 DPI (dots per inch) at the size the image will print. Every major print-on-demand platform (Amazon KDP, IngramSpark, Lulu, Blurb, and BookBaby) requires or strongly recommends 300 DPI for interior images. Fall below it and your printed photographs, illustrations, and diagrams look soft or pixelated; go far above it and you only bloat the file with no visible gain.

Understanding what DPI actually measures, how to check it, and what happens when you get it wrong will save you from costly reprints and production delays.

What Is the Difference Between DPI and PPI?

Authors meet both terms, DPI and PPI, and the industry uses them almost interchangeably, which breeds confusion. Strictly, DPI (dots per inch) is the density of physical ink dots a printer lays on paper, while PPI (pixels per inch) is the density of pixels in a digital file. When a platform says “submit images at 300 DPI,” it means your source file should be 300 PPI at its intended print size, so the printer can reproduce it at the matching dot density.

For manuscript preparation the distinction rarely matters in practice. What matters is that the number in your image’s properties reads 300 (whether labelled DPI or PPI) at the physical size you intend to print it. If your editor shows 72 PPI, the web default, that image is not print-ready no matter how sharp it looks on screen. The most useful habit is to always think about resolution and print size together, because a figure that is 300 PPI at postage-stamp size is only 75 PPI once you stretch it across half a page.

Why Is 300 DPI the Universal Standard?

The 300 DPI standard exists because of how human vision works at reading distance. At roughly 10–14 inches from the page, the distance most people hold a book, the eye resolves detail down to about 300 dots per inch. Below that, printed images look grainy; above it, the eye perceives no improvement.

Lulu has publicly tested print quality at multiple resolutions and settled on 300 PPI as optimal, noting that images above 600 PPI show negligible gain while inflating file size. Amazon KDP sets no maximum DPI but warns that excessively high resolutions can cause processing issues. In practice there is no reason to exceed 300 DPI for photographs or 400 DPI for images that contain small text, such as charts or infographics. When authors send us image-heavy interiors, over-sized files cause upload and preflight headaches far more often than they improve the printed page, so more is not better past the threshold. A 300-page illustrated book saved with every image at 600 PPI can easily double the size of the exported PDF without a single reader ever seeing the difference, and that extra weight is exactly what stalls uploads and trips processing limits.

What Are the Platform-Specific Requirements?

While 300 DPI is the universal target, each platform enforces it a little differently:

The practical takeaway from this table is that IngramSpark’s 72 PPI floor is a hard automated gate, per its File Creation Guide: a single low-resolution image will stop the whole file at preflight. Blurb’s image resolution guidelines add a ceiling most authors never think about, a 75-megapixel maximum per image, which a very large scanned illustration can exceed. If you publish the same interior to more than one platform, prepare to the strictest requirement (300 PPI, no image under 72 PPI or over 75 megapixels) so one file clears everywhere.

What Happens When DPI Is Too Low?

Low DPI produces a set of specific, recognisable defects in a printed book. Photographs look pixelated, with visible squares of colour instead of smooth gradation. Lines and curves develop jagged, staircase edges. Fine detail in illustrations vanishes. Text baked into images (captions, chart labels, infographic copy) turns blurry or illegible.

The usual culprit is web-optimised imagery. Pictures pulled from websites, social media, or online libraries are typically saved at 72 PPI, fine for screens and useless for print; a photo that looks crisp on your monitor prints at roughly a quarter of the detail a press needs. The trap is that none of this shows on your monitor, where a 72 PPI image can look perfect; the shortfall only appears once the press renders it at physical size. These defects are irreversible once the book is printed, and most platforms will not offer reprints or refunds for quality problems caused by source resolution. The same low-resolution source, incidentally, causes the blurry images authors see in Kindle ebooks, so fixing your originals improves both editions at once.

How Do You Check and Calculate DPI?

Before submitting, verify every interior image meets 300 DPI at its intended print size. The calculation is simple: required pixels = print width in inches × DPI. A 4-inch-wide image at 300 DPI needs to be at least 1,200 pixels wide. A full-page image on a 6″ × 9″ trim (roughly 5 inches of printable width after margins) needs at least 1,500 pixels across.

In Adobe Photoshop, open Image → Image Size and read the resolution field with “Resample” unchecked, which shows the true resolution at the image’s physical print dimensions. In free tools such as GIMP or IrfanView the same figures appear in the image properties dialog. On a Mac, right-click any image file, choose Get Info, and look under More Info for the DPI field. Whichever tool you use, check resolution at the size the image is actually placed in the layout, not at its raw pixel dimensions; the two are only the same when the image fills exactly the space its pixel count supports at 300 PPI. For a book with many figures, it is worth building a quick checklist of each image’s placed width and required pixel count, so a single under-sized figure does not slip through to preflight and stall the whole upload.

One warning matters above the rest: upsampling does not work. Artificially raising DPI, turning a 72 PPI image into 300 PPI with resampling on, adds no real detail; it stretches existing pixels into soft, interpolated mush that still prints poorly. If your source is 72 PPI, you need a higher-resolution original, not a resampled copy, because no software can invent detail that was never captured in the first place. When an author cannot find a better original, it is almost always faster to recreate a chart or diagram from scratch at full resolution than to try to rescue the low-resolution version.

How Should You Prepare Interior Images?

Start with the highest-resolution source files you can get. If you are commissioning illustrations or shooting photographs for the book, capture them well above 300 DPI at the intended print size, which leaves room to crop and adjust without dropping below the threshold.

Export the final manuscript as a PDF. PDF is the preferred submission format for every major platform because it preserves resolution, layout, and colour on export. Avoid submitting Word files directly when the book contains images, because Word can silently compress your images and quietly undo your resolution work. Treat line art differently from photographs. Pure black-and-white drawings, maps, and pen illustrations have hard edges that show jaggedness far more readily than a photo, so they benefit from 600 to 1200 DPI rather than 300; the higher density keeps thin lines crisp and avoids the stair-stepping that 300 DPI can leave on a fine diagonal. Mind colour space as well as resolution: convert images to grayscale for black-and-white interiors, and check each platform’s colour requirement for colour interiors (Lulu recommends sRGB, while IngramSpark expects CMYK for colour work). Finally, if an image carries embedded text, charts, diagrams, annotated photos, target 400 DPI rather than 300 so the small type stays sharp; this is the same reasoning behind avoiding blurry text inside images at print size.

Frequently Asked Questions

Is 300 DPI enough for a full-page photo in my book?

Yes, as long as the image is 300 PPI at the full print size, not at a smaller size then enlarged. For a full-page photo on a 6″ × 9″ trim, that means roughly 1,500 pixels across the printable width and about 2,550 down the printable height. Check the resolution at the final placed dimensions, because an image that is 300 PPI at 3 inches wide drops well below the threshold once stretched to fill the page.

Can I increase a low-resolution image to 300 DPI in Photoshop?

Not usefully. Turning on resampling to raise the DPI stretches the existing pixels and interpolates new ones, which produces a soft, artificial result that still prints poorly. Real resolution has to come from a higher-quality original or a freshly created file; upsampling only changes the number, not the actual detail.

Do ebook images need to be 300 DPI too?

No. Ebook images are displayed on screens, so resolution is measured in total pixels rather than DPI, and 72–150 DPI equivalents are usually fine. The 300 DPI rule applies to print interiors; if you publish both a print and an ebook edition, prepare high-resolution originals for print and let the ebook conversion downscale from them.

What DPI should charts and text-based graphics be?

Target 400 DPI for any image that contains small text, such as charts, graphs, tables, or annotated diagrams. The higher density keeps thin strokes and small type crisp in print, where 300 DPI can leave fine lettering slightly soft. Better still, where possible set such text as live text in the layout rather than baking it into an image.

Why did my book get rejected for low-resolution images?

Most often because at least one interior image fell below the platform’s floor at its placed size; IngramSpark, for example, rejects files containing any image under 72 PPI, and BookBaby holds orders when preflight detects low resolution. The fix is to locate the offending image, replace it with a version that is at least 300 PPI at print size, and re-export the PDF before resubmitting.