PDF to JPG

Two numbers decide what you get

The first is resolution. A PDF page has no pixels in it: it is drawing instructions on a grid measured in inches, so something has to decide how finely to draw them. 150 dots per inch is the default here and makes an A4 page about 1,240 by 1,753 pixels, which is sharp on any screen. 300 is what a printer expects. 600 is for when you are going to crop into a corner of the page. The pixel size is shown next to the save button, so you are choosing a result rather than guessing at a multiplier.

The second is JPEG quality. At 90 percent, the default, a page is indistinguishable from the document at any normal size. Below about 70 the letters start to show a faint grey mist along their edges, because that is what JPEG does to hard lines. If the pages are dense text and quality matters, PDF to PNG has no quality setting at all, because it loses nothing.

Usually you want one page, not all of them

The real job is almost never "convert this document". It is "get me page seven", "send them the signature page", "put the floor plan in the listing". So the pages are laid out as pages: tick the ones you want, or type a range the way you would say it out loud, 1-3, 7, or 12-. One page comes down as a JPG; several arrive as a single ZIP, numbered so that a folder sorts them in reading order.

Long documents open immediately, because the thumbnails are drawn only as you scroll to them, and pages are rendered one at a time while saving so the tab keeps answering.

The document stays with you

This is the part worth being fussy about. A photograph pasted into a free converter is usually a holiday snap; a PDF pasted into one is usually a contract, an invoice, a payslip, a bank statement or a medical letter. Those services upload your file, convert it on a machine you cannot see, and keep it for some period described in a policy you did not read.

Here the renderer is pdf.js, Mozilla's, served from this site as an ordinary file and run inside your tab. There is no address on this site that could receive a document, and the password of a locked PDF is used in the same place. Check it: load the page, turn the browser offline, convert a PDF anyway.

Going back the other way

JPG to PDF turns photos back into a document, and it copies each JPEG into the file rather than re-compressing it, so a round trip does not cost a second generation. For a mixture of formats there is image to PDF, and for iPhone photos HEIC to PDF.