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How to convert a PDF to JPG on a Mac

Preview writes one sheet per trip through the dialog. What its pixels-per-inch box decides, an Automator route for whole documents, and two traps.

Updated 2026-08-06

Preview does it, and for a single page it is the shortest route there is. The catch turns up at the second sheet: one trip through the dialog yields one image, so a twelve-page document is twelve trips unless you build something first.

What the density figure in that dialog is deciding, and why a rendered sheet is a picture of words rather than words, belong to converting a PDF to JPG. Everything below is the machinery on your own machine.

Exporting a sheet from Preview

  1. Double-click the document. Preview is the default handler, so nothing else is needed.
  2. Bring up the sidebar — the View menu, then Thumbnails — and click the sheet you want. Whatever is showing is what gets written.
  3. In the File menu choose Export. Not Save As, and specifically not Export as PDF, which sits beside it in the same menu and catches people every day.
  4. Open the Format pop-up and take JPEG.
  5. Two controls unfold beneath it: a compression slider, and a figure in pixels per inch.
  6. Name the file, pick a folder, save.

The slider behaves as you expect. The other control does not.

Why a pixels-per-inch box appears here and nowhere else

Because there are no pixels yet. A PDF page records a width and a height in points, of which there are seventy-two to an inch, alongside instructions for the marks to put on it. Nothing in the file says how many dots wide anything should be. An existing photograph carries its own grid and can only ever be scaled up or down from it; a page carries none, so a number has to be invented before an image can exist at all, and this box is where the invention happens. It is not metadata. It is the whole result.

Both dimensions scale with whatever you type, so the pixel count and the file grow with its square: double the figure and you quadruple the output. That is the one setting worth thinking about before you press save.

One sheet at a time, and what to do about twelve

Selecting several thumbnails does not change the arithmetic. The File menu will happily export the selection, but what it writes is another PDF holding the pages you picked — a subset of the document, not pictures of it. No built-in path runs from a whole document to a folder of JPEGs.

Automator closes the gap. Open it, start a Quick Action, and set the workflow to receive PDF files in the Finder. In the action list, search for PDF and take the action whose name says it renders pages as images: it carries its own format menu and its own density field, and it writes one file per page. Save it under a name you will recognize and it joins the Quick Actions section of the Finder’s right-click menu.

Worth knowing before you build it: the Convert Image entry already in that menu is a different thing. It appears for image files — HEIC, PNG, TIFF — and a PDF is not one of those. The action you build is what fills the hole it leaves.

If none of that sounds like a good use of an afternoon, the PDF to JPG converter here takes the whole document in one pass, states the pixel dimensions of every page before it renders anything, and runs inside the browser already open on the same Mac.

Quick Look shows you the page without handing it over

Press Space on a document in the Finder and it appears immediately, rendered at full quality, sharp enough to read. Nothing about it is a file. The panel draws the page on demand and discards the drawing when it closes; there is nothing to drag out of it, and the buttons in its corner open the document elsewhere or share the document itself. The preview column in the Finder’s gallery view is the same panel with different furniture.

Worth naming, because the gap is invisible: the image looks like it exists, and people lose real time trying to retrieve something that was never there.

The screenshot, and why a Retina display makes it look like it worked

Command-Shift-4 over a page in Preview produces something convincing. A Retina display holds two device pixels for every point of layout, and screen capture records the device pixels, so a sheet filling half a large display can come back a couple of thousand pixels tall and look immaculate on the machine that shot it.

It still is not a conversion. The window is a hard ceiling — whatever zoom Preview was sitting at is the most detail the capture can hold — and a full sheet at print density runs to about 2550 by 3300 pixels, which no window on any Mac is showing. Window furniture arrives in the frame. And macOS writes screenshots as PNG, so a form demanding JPEG is still unsatisfied.

That last point cuts the other way for text. If the pages are type, tables or line art, lossless is the format you wanted from the start, and PDF to PNG does the same rendering without the fringing JPEG leaves around letterforms. When it is the words themselves you are after rather than their appearance, extracting the text reads them straight out of the document instead.