Rotate PDF

Why your reader's rotate button does not stick

Most PDF readers have a rotate control in the toolbar, and for most people it appears to do nothing lasting. That is because it changes the view, not the document — close the file and reopen it and the page is sideways again. Some readers offer to save the rotation, many do not, and browser-based readers almost never do.

This tool writes the rotation into the page objects themselves. Every PDF page carries a /Rotate entry which tells any reader how many degrees to turn it before display. Setting that value is what makes the change permanent and portable: the page will appear correctly in Acrobat, in Preview, in Chrome, and on a printer.

Because rotation is metadata rather than pixels, nothing is re-rendered. There is no quality loss, no increase in file size, and text remains selectable and searchable exactly as before.

Rotation is cumulative

The angle you choose is added to whatever rotation the page already has, then normalised into the range 0–270. A page already at 90° that you rotate by another 90° ends up at 180°, not back at 90°.

This matters when a document mixes orientations, which scanned files very often do. If a batch scanner fed some sheets in landscape, those pages may already carry a 90° rotation while the rest sit at 0°. Applying a blanket rotation to the whole document will fix one group and break the other.

The reliable approach with mixed documents is to rotate the affected pages only, using the page range field, and to run the tool more than once if different pages need different corrections. Rotating in two passes produces exactly the same result as one combined rotation.

Rotation versus a genuinely landscape page

There is a difference between a portrait page rotated 90° and a page that is natively landscape, and the distinction shows up at print time. A rotated page keeps its original media box — a tall rectangle — and simply instructs the reader to display it turned. A native landscape page has a wide media box.

For screen reading this makes no difference. For printing it sometimes does: some print drivers honour the rotation and some fit to the media box, which can produce an unexpectedly scaled or clipped result. If a rotated document prints wrongly, printing to a new PDF from your reader will bake the rotation into the geometry and usually resolves it.

Fixing scans that came out upside down

The most common real use of this tool is a document scanner that fed pages the wrong way. Two symptoms are worth telling apart. If every page is upside down, the stack went in backwards and a single 180° rotation on all pages fixes it. If alternate pages are upside down, the scanner was in duplex mode with the wrong binding-edge setting, and you need to rotate only the even pages — type a range like 2, 4, 6, 8 rather than rotating everything.

If pages are sideways rather than inverted, the sheets were fed in landscape. 90° clockwise or anti-clockwise puts them right, and you can tell which by looking at where the text starts: if the first line runs up the left edge, rotate clockwise.