How PDF to JPG works
A PDF page is a set of drawing instructions: put this text here, draw this line, place this photo there. To make an image, the tool follows those instructions on a blank canvas with a grid of pixels, exactly the way a PDF reader draws a page on screen, then saves the canvas as a JPG or PNG file.
It uses PDF.js, the PDF engine built into Firefox, running inside your browser. The PDF is never uploaded. Pages are drawn one at a time, so even long documents convert without freezing the page.
Picking a resolution
Resolution, measured in dots per inch (dpi), decides how many pixels each inch of the page gets.
| Resolution | US Letter page (8.5 × 11 in) | A4 page (8.27 × 11.69 in) | Use it for |
|---|---|---|---|
| 72 dpi | 612 × 792 px | 595 × 842 px | Quick previews, web pages |
| 150 dpi | 1,275 × 1,650 px | 1,240 × 1,754 px | Slides, chat apps, documents on screen |
| 300 dpi | 2,550 × 3,300 px | 2,480 × 3,508 px | Printing, zooming into fine print |
Going from 150 to 300 dpi doubles the width and height, so the image has four times as many pixels and the file is roughly three to four times bigger.
JPG or PNG?
- JPG uses lossy compression. At 80–90% quality it looks the same as the page to the eye, and files are small. Choose it for scans, photos and anything you will email.
- PNG is lossless. Every pixel is kept exactly, which keeps small text and thin lines razor sharp. Choose it for diagrams, screenshots for documentation, or if you will edit the image later. Expect larger files.
Worked example
You need page 4 of a 20-page product manual, a wiring diagram, as an image to paste into a support ticket.
- Choose the PDF. Every page starts ticked.
- Press None, then tap the page 4 thumbnail. The note reads “1 of 20 pages selected”.
- Choose PNG for the crisp lines and 150 dpi.
- Click Convert 1 page to PNG. The download is
manual-page-04.png, about 1,275 × 1,650 pixels for a Letter-size page.
Converting the whole manual instead gives a ZIP with manual-page-01.jpg to manual-page-20.jpg. The page numbers are padded with zeros so the files sort in the right order in any folder.
Tips
- Need the text, not a picture? PDF to Text copies the words out of the PDF so you can edit them.
- Images too big for a form? Shrink them with Compress Image or change their dimensions with Resize Image.
- Going the other way? JPG to PDF turns photos back into a single PDF.
- Only a few pages? You can also pull them into a smaller PDF with Extract PDF Pages.
- Phones have less memory. For large documents at 300 dpi on a phone, convert in smaller batches of pages.
For device-by-device steps on Windows, Mac, iPhone and Android, and tips for keeping small text sharp, read our guide on how to convert a PDF to JPG.
Privacy
The PDF is read and drawn entirely on your device. No copy is sent to a server, and the images are created in your browser’s memory until you download them.