Converting a PDF to JPG means rendering each PDF page into a JPEG image. A PDF is a layout document — it contains instructions for placing text, fonts, and graphics. A JPG is a pixel grid. The conversion is a rendering step: the PDF is drawn at a chosen resolution, and the result is saved as a compressed image.
This is not the same as changing a file extension. Renaming a PDF to .jpg produces a broken file. Actual conversion needs software to interpret the PDF and produce real image data.
What DPI means and why 300 is the standard
DPI — dots per inch — is the resolution of the output image. It controls how many pixels represent each inch of the original page. An A4 page (8.27 inches wide) at 150 DPI comes out 1240 pixels wide. At 300 DPI it comes out 2481 pixels wide — twice the resolution, four times the pixel count.
300 DPI is the standard for print and archival because text and fine lines stay sharp when you zoom in or print the image. 150 DPI is enough for screen viewing, and produces a smaller file. The right choice depends on what you will do with the image: if it might be printed, enlarged, or submitted to a system that checks image quality, use 300 DPI. If it is only for screen display or thumbnail use, 150 DPI is sufficient.
Filum's PDF to JPG tool converts at 300 DPI, measured: an A4 page in the output is 2481 pixels wide.
Why most converters upload your file
Most online PDF-to-JPG tools send your PDF to a server, render it there, and return the image. This works, but it means a copy of your document passes through a third-party system — relevant for contracts, identity documents, financial records, or anything you would not share publicly.
Browser-side rendering is now capable enough to do this on your device. The same rendering engine (pdf.js) that powers Firefox's built-in PDF viewer can be used to render pages to an image canvas. The conversion runs entirely in your browser, and the file never leaves your computer.
What a JPG can and cannot do
A JPG image of a PDF page is not editable in the way a Word document is. The text is rasterised — it is pixels, not characters. You cannot search it, copy text from it, or change a word without image editing software. If you need editable text, convert to PDF to Word or PDF to Text instead.
What a JPG does well: it is universally compatible, opens on any device or operating system, and is expected by many systems that accept documents (email attachments, form uploads, print services). It is the right format when you need the page as an image rather than as a document.
Common use cases
Email attachments: some email systems block PDF attachments but accept images. Converting a one-page letter or invoice to JPG before attaching removes the friction.
Slide inserts: presentation software (PowerPoint, Keynote, Google Slides) lets you insert images directly. Converting PDF pages to JPG is the simplest way to embed a document page in a slide.
Archiving scans: scanned physical documents are often stored as image archives. Converting a PDF scan to individual JPG pages makes it compatible with image library tools and storage systems that do not handle PDFs.
Thumbnail generation: a JPG of the first page of a PDF is easy to use as a preview image in a web app, a document management system, or a file listing.
How to do it
Open the PDF to JPG tool at filum.se/pdf/pdf-to-jpg. Drop your PDF onto the upload area. The tool renders each page on your device at 300 DPI and produces a JPG for each page. Multi-page PDFs are packaged as a ZIP archive. There is no upload, no account, and it works with your internet connection switched off once the page has loaded.
You will see the page count and the pixel width of the output before downloading, so you can confirm the resolution is what you expected. For a single page, the download is a JPG file directly. For multiple pages, it is a ZIP containing numbered JPG files in page order.