Why convert a PDF to PNG?
A PDF is a document; a PNG is an image. You need the image when a PDF won’t go where you want it to:
- Slides, websites and social posts. Presentation apps, website builders and social networks take images, not PDF pages.
- Previews and thumbnails. A PNG of the first page shows what a report or menu looks like without opening a PDF viewer.
- Image editors. Cropping, annotating or retouching a page is easier in an image editor.
- Upload forms that only accept images. Some sites want a JPG or PNG of a certificate or form, even though you have a PDF.
PNG is the right image format for most PDF pages. It’s lossless, so text, lines and charts stay crisp with none of the blurry halo that JPG compression leaves around letters.
Choosing a resolution
PDF pages are measured in inches, not pixels, so the resolution (dots per inch, DPI) decides how many pixels each page gets:
| Resolution | US Letter page | A4 page | Good for |
|---|---|---|---|
| 72 DPI | 612 × 792 px | 595 × 842 px | Thumbnails, quick previews |
| 150 DPI | 1275 × 1650 px | 1240 × 1754 px | Screens, slides, documents, email |
| 300 DPI | 2550 × 3300 px | 2480 × 3508 px | Printing, zooming into small print |
Higher resolutions make larger files: a 300 DPI page has four times the pixels of a 150 DPI page. For a scanned PDF, choosing a resolution above the original scan’s adds pixels but not detail.
How the conversion works
Each page is drawn with PDF.js, Mozilla’s open-source PDF engine, the same one Firefox uses to show PDFs. Pages are drawn as they would print: fonts embedded in the PDF are used, page rotation is respected, filled-in form fields appear with their values, and the background is white, as on paper.
Multi-page PDFs come back as one PNG per page, named after the file: report-page-1.png, report-page-2.png and so on, padded with zeros for long documents so they sort in order. Everything runs on your device, and nothing is uploaded at any point.
Going the other way? HEIC to PDF and TIFF to PDF turn images into PDF pages.