Why you would want a picture instead of a PDF
PDF is a container for pages; JPG is a container for an image. The difference matters the moment you need to put a page somewhere that only accepts pictures.
WhatsApp previews of PDFs are unreadable without opening the file, and many people simply will not open one. A presentation slide needs a picture, not an embedded PDF object. A website’s product gallery, a class assignment, a thumbnail for a listing, a photo caption in a report — all of them want an image file. Some social platforms and marketplaces reject PDFs outright.
Screenshots are the usual workaround, and they are a poor one: they capture only what is on screen at the current zoom, they include your browser chrome if you are not careful, and the resulting resolution depends on your monitor rather than the document.
Choosing the right resolution for the job
Resolution is expressed in DPI — dots per inch of the printed page. The PDF itself does not have a resolution; it has vector instructions and embedded images, and the DPI setting decides how many pixels to generate per inch of page.
72 DPI produces a page about 600 × 850 pixels for A4. Fine as a thumbnail or a quick screen reference, visibly soft on a large monitor.
150 DPI gives roughly 1240 × 1750 pixels. This is the sweet spot for sharing: sharp on any phone or laptop screen, prints acceptably at A4, and keeps file sizes reasonable.
200 DPI is a good compromise for documents that will be printed on a home printer. 300 DPI yields about 2480 × 3508 pixels for A4 — the standard for commercial printing and for anything that will be zoomed into or cropped later.
Remember the trade: doubling the DPI quadruples the pixel count and roughly quadruples the file size. A 20-page document at 300 DPI can easily produce 60 MB of images.
Practical uses and the right settings for each
Sharing a form on WhatsApp: 150 DPI with quality around 80%, converting only the relevant page range. Clear on a phone, small enough to send quickly on a mobile connection.
Adding a page to a PowerPoint slide: 150 DPI is plenty for a projector, and the JPEG drops straight onto the slide with no conversion step.
Printing a poster or a large diagram: 300 DPI, quality 95%, downscaling off. Check that the page range is set so you are not exporting a hundred unused pages.
Creating a preview thumbnail: use 72 DPI and only the first page. The result is a few tens of kilobytes and loads instantly.
Feeding a document into an app that only accepts images: 200 DPI and grayscale usually gives the best balance of legibility and size.
What does not survive the conversion
An honest list, because it affects which tool you should choose. Text is no longer selectable or searchable — it becomes pixels. Links inside the page stop working. Form fields and buttons become flat artwork. Screen readers cannot read the page. And if you convert a multi-page document into images, you lose the page sequence unless the viewer sorts by name, which is why the exported files are zero-padded.
If any of those matter, the PDF itself is the right format and you should keep it as a PDF. Convert to JPG when you need a picture somewhere, and keep the original PDF for everything else.
For extraction where you want to keep selectable text rather than a picture, the PDF to Text tool is the right choice. For pulling out only the photographs already embedded in a PDF, extract the original images with Extract Images instead — that preserves their exact pixels rather than re-rendering a whole page.
One more consideration for anyone exporting a document for an official submission: check whether the recipient actually wants images. Many government and university portals ask for a PDF precisely because a stack of JPEGs has no page order, no page size and no way to be verified as a single document. Export to JPG when a person or a system needs a picture, and keep PDFs as PDFs otherwise.