JPG or PNG: choosing by content and purpose
Both formats hold the same thing here: a picture of the page, drawn at the resolution you chose, on a white background, with the same pixel size. What differs is how those pixels are stored — and that changes the file size and how fine edges look.
The short answer
- JPG for everyday use: sharing in a chat, an email, a slide, a web page. On pages with photographs it is usually far smaller.
- PNG for text, charts, diagrams and screenshots, when clean edges around letters and lines matter more than file size.
If you are not sure, start with JPG (the default) and look at the result. If the letters show a faint haze or blotches around them when you zoom in, save the same pages again as PNG.
How each format stores the page
JPG compresses with loss: it simplifies fine detail that the eye notices little, which is why photographs get small. PDF to Image saves JPG at one fixed quality setting; there is no quality slider. On sharp, high-contrast edges — black text on white — that compression can leave faint artefacts.
PNG compresses without loss: once the page has been drawn as pixels, those pixels are stored unchanged. That is all “lossless” covers. It does not keep the PDF as a PDF, it does not add detail the chosen resolution did not capture, and it does not keep text selectable or links working. The page is drawn first; only after that does PNG lose nothing.
Measured file sizes
We saved the same three A4 pages of a test PDF in both formats. Page 1 is a full-page photograph, page 2 is half photo and half text, page 3 is text. Sizes are in MB, in Chromium (the engine of Chrome and Edge) and WebKit (the engine of Safari):
| Page · dpi | JPG Chromium | PNG Chromium | JPG WebKit | PNG WebKit |
|---|---|---|---|---|
| Photo · 150 | 0.25 MB | 4.00 MB | 0.49 MB | 3.45 MB |
| Photo · 300 | 0.85 MB | 13.22 MB | 1.69 MB | 11.53 MB |
| Half photo · 150 | 0.23 MB | 1.25 MB | 0.37 MB | 1.16 MB |
| Half photo · 300 | 0.64 MB | 4.42 MB | 1.10 MB | 3.97 MB |
| Text · 150 | 0.37 MB | 0.50 MB | 0.59 MB | 0.48 MB |
| Text · 300 | 0.94 MB | 1.26 MB | 1.51 MB | 1.14 MB |
The pixel size was the same in every pair (1240 × 1754 px at 150 dpi, 2479 × 3508 px at 300 dpi). The images are made by your browser’s own encoders, so the same page gives different file sizes in different browsers.
JPG is not always smaller
On the photo pages, JPG was about 7 to 16 times smaller. On the text page the gap was small — and in WebKit it went the other way: the PNG was smaller than the JPG at both resolutions. A page with large flat areas of colour, such as a simple bar chart, showed the same in WebKit (about 49 KB as PNG and 70 KB as JPG at 150 dpi). In Chromium, JPG stayed the smaller file on all of these pages.
So the rule of thumb is about content, not format names: photographs and scans favour JPG; text and flat graphics bring the two close, and PNG may even come out smaller.
Choose by what happens next
| The image will… | Start with |
|---|---|
| go into a chat, an email or a document | JPG |
| show a photo, a scan or a page with pictures | JPG |
| show small print, thin lines, a chart or a diagram | PNG |
| be edited further, or saved again many times | PNG |
| need a transparent background (both are drawn on white) | neither |
When you always need the same format
PDF to Image is built for switching: changing the format keeps your PDF, your page selection and the resolution. If you always want one format, PDF to JPG and PDF to PNG do the same job with a single format and no choice to make.
Resolution affects size as much as the format does; Resolution and large pages covers that.
Convert your pages in the browser → PDF to Image