Choosing a resolution when converting a PDF to images: 72 / 150 / 300 DPI
For screens, for articles, for the printer — pick the wrong DPI and you get either a blurry image or a painfully large file. I exported the same PDF at three levels and here is the conclusion.
I helped a marketing colleague turn a product manual PDF into JPGs for a social post. She picked the highest resolution by default, and one image came out at 8MB, so the upload timed out. On the other side, the designer complained that the 72 DPI export turned into a mosaic when zoomed in. Choosing DPI well saves half the work.
What DPI means (in plain words)
DPI is how many pixels fit into one inch. The larger the number, the more detail an image of the same size carries — and the larger the file becomes. A PDF mixes vector content with embedded images, so when you turn it into a bitmap you have to decide how much detail you want.
Three levels, measured on the same document
I exported the same 10-page, mixed text-and-image PDF at three levels with PDF to Images:
72 DPI — screen browsing
- Look: fine full-screen on a phone, blurry once you zoom past 150%.
- Per page: roughly 200–400KB, depending on the content.
- Good for: quick previews, thumbnails, images for an internal wiki.
150 DPI — my everyday default
- Look: crisp on a Retina screen, still readable when printed on A5.
- Per page: roughly 800KB–1.5MB.
- Good for: article illustrations, chat documents, images in the body of an email.
300 DPI — print quality
- Look: edges stay clean when you zoom in.
- Per page: often 4–10 times the size of the 72 DPI version.
- Good for: sending to a printer, formal archiving, replacing a scanned document for legal purposes.
[Image: the same page zoomed in at 72 / 150 / 300]
Which level for which job
| Purpose | Suggested DPI | Tool |
|---|---|---|
| A long image for social posts | 150, width 1080px | PDF to Long Image |
| A ZIP of individual JPGs | 150 | PDF to Images |
| A printed poster | 300 | PDF to Images |
| Just readable text | 72 is enough | PDF to Images |
File size and speed
Exporting a 50-page manual at 300 DPI took me close to two minutes on a laptop, and the ZIP came to over 200MB. The same pages at 150 DPI were about 40MB and felt noticeably faster. Higher is not better — enough is better.
Long image versus separate pages
- You want to scroll through it: use PDF to Long Image with a width of 1080 or 750; in a long image the DPI idea shows up as the output width.
- You want to edit page by page: export a ZIP with PDF to Images.
The end
My rule now: 150 for anything shared publicly, 300 for printing and archiving, 72 when I just need to take a quick look. Decide where the image will end up first, then pick a level, and you will not get caught out by file size.
Have a go → open PDF to Images, export the same PDF at 72 and at 150, and compare them yourself.