Image resolution too low (under 300 DPI): fixing picture warnings for KDP, Lulu and IngramSpark

Resolution is how many dots of picture are packed into each inch of the printed page. You'll see it written as DPI (dots per inch) or PPI (pixels per inch); for this purpose they mean the same thing. The more dots per inch, the sharper the print.

A photo 1,800 pixels wide printed 6 inches wide is 300 PPI. Stretch the same photo to 9 inches wide and it drops to 200 PPI, and looks softer. A quick rule: width in pixels ÷ 300 = the widest you can print it, in inches, at 300 PPI.

The numbers each platform uses (as at 4 October 2026)

KDP asks for interior images of at least 300 DPI, and calls anything under 200 DPI low resolution. It recommends no more than 600 DPI, to keep your file under its 650 MB limit. Covers need at least 300 DPI too. Its formatting help names two common causes: pictures enlarged after they were placed, and Word compressing images when it saves.

Lulu asks for 300 to 600 PPI. Below 200 it shows a warning (orange, not a red error): "Your file contains images with a resolution less than 200 pixels per inch."

IngramSpark checks for "Low-resolution images" at upload. It asks for 300 PPI for photos and greyscale images, and 600 PPI for black-and-white line art (drawings with no shades of grey). Interior images under 72 PPI are rejected, and cover images under 200 PPI may be.

Barnes & Noble Press recommends 300 DPI. Lower-resolution images still pass its checks, but it won't promise how they'll print.

How to fix it in Word

Word can reduce the quality of pictures when it saves, to make the file smaller. Turn that off first, then put the originals back.

1. Go to File > Options > Advanced. Under Image Size and Quality, tick "Do not compress images in file" and set "Default resolution" to High fidelity.
2. Find the original picture files: the photo from your camera, the file from your illustrator. Not a copy from a website, email or screenshot.
3. Replace each picture: right-click it, choose Change Picture > From a File, and pick the original. That keeps it in the same place. Pictures Word has already compressed can't be restored any other way.
4. Don't stretch a small picture bigger. If it needs to print larger, you need a bigger original.
5. Don't use Picture Format > Compress Pictures.
6. Save as PDF with Standard (publishing online and printing) selected, not "Minimum size".

Enlarging a small image in a photo program doesn't fix it either. It adds pixels, not detail, so the check may pass while the print still looks soft. If you only have a small version, print it smaller.

Using a designer, InDesign, Affinity or Canva? Place images at 300 PPI at the size they'll print (600 for line art), and turn off downsampling, which lowers resolution, when you export the PDF. KDP's recommended PDF settings have it switched off.

Check before you upload

Bervet's free spine width calculator checks interior and cover PDFs, including the resolution of every image at the size it's placed. The check runs in your browser and nothing is uploaded; checking a PDF needs a free Bervet account.