PDF & Image DPI Checker for Print Books
Find out if your pictures are sharp enough to print. Check a whole PDF at once, or one picture. You see the real DPI at the size it prints. Nothing is uploaded; it all happens on your device.
What is a DPI check? A DPI check (also called a resolution check) tells you how many pixels each picture has for every inch it prints. Printers like Amazon KDP and IngramSpark ask for 300 DPI. Below about 200 DPI, pictures can print soft or blurry. This free PDF resolution checker shows the real number for every picture in your file.
Check a whole PDF
Your book's cover or interior PDF. Every picture on every page is checked at the size it's placed.
Check one picture
Why 300 DPI matters for print
DPI (dots per inch) is how many pixels of your picture land in each printed inch. Screens look fine at 72 to 150, but paper shows every missing pixel. Printers ask for 300 DPI at the size it prints. A picture that looks sharp on your phone can still print blurry on a cover.
The "DPI" number in your file doesn't matter. Pixels do.
A photo can say "300 DPI" in its settings and still be too small. What counts is the number of pixels compared to the printed size. To print 6" wide at 300 DPI you need 6 x 300 = 1,800 pixels across. This checker does that math for you.
Pixels you need for common covers (300 DPI)
| Book size | Front cover with bleed | Pixels needed |
|---|---|---|
| 5" x 8" | 5.125" x 8.25" | 1,538 x 2,475 |
| 5.5" x 8.5" | 5.625" x 8.75" | 1,688 x 2,625 |
| 6" x 9" | 6.125" x 9.25" | 1,838 x 2,775 |
| 8.5" x 11" | 8.625" x 11.25" | 2,588 x 3,375 |
A full wrap cover (back, spine and front) needs more: use the KDP cover calculator to get its pixel size.
How to check the DPI of a PDF
Drop your PDF into the checker at the top of this page. It finds every picture on every page and divides each picture's pixels by the size it is placed on the page. A 1,200-pixel-wide photo placed 4 inches wide is 300 DPI; the same photo stretched to 6 inches is only 200 DPI. That is the number KDP and IngramSpark care about, not the "DPI" saved in the picture's settings.
What to do if your picture is too small
- Find the original, full-size file (not one saved from email, a website or social media, which shrink pictures).
- Buy or download the largest size from the stock photo site.
- Print it smaller. The checker shows the biggest size that still reaches 300 DPI.
- Simply changing the DPI number in Photoshop without adding pixels does not fix it.
Want every picture checked at once?
SparkPrep checks your whole cover and every interior page against your printer's rules, including image resolution, bleed, fonts, color and ink. It explains every problem in plain English and fixes what it can for you.
Check my book files Format my book freeQuick answers
What DPI does KDP require?
KDP recommends 300 DPI for images in print books and warns about images below that in its previewer.
How do I check the DPI of an image?
Divide the picture's width in pixels by the width in inches it will print. 1,800 pixels printed 6 inches wide is 300 DPI. This free checker does it for you.
How do I check the resolution of a PDF?
Drop your PDF into the checker above. It lists every picture on every page with its real DPI at the size it prints, and flags anything under 300 DPI. It's free and nothing is uploaded.
Does this tool upload my picture?
No. The picture is read in your own browser and never leaves your device.
More free tools
- KDP cover size calculator and template
- Book spine width calculator
- Book margin and bleed calculator
- Word count to page count calculator
- Book cover dimensions by trim size
- All free tools
SparkPrep is an independent tool and is not affiliated with Amazon KDP, IngramSpark, Barnes & Noble Press or Lulu. Always check your printer's own help pages before you upload.