Why a rotated PDF goes back to how it was

Two different rotations

Every page in a PDF carries a rotation attribute: a number, 0, 90, 180 or 270, that tells a reader how far to turn the page before displaying it. The marks on the page do not move. The instruction to turn them does.

So there are two quite different things a program can do when you press a rotate button:

• Turn the view. Temporary, local to your screen, gone when you close the file. Nothing is written.
• Change the attribute and save. Permanent, travels with the file, and everyone who opens it afterwards sees it upright.

Most built-in viewers — browsers included — do the first. It looks like the second, which is the whole problem.

Making it stick

Use a tool that writes the file back out. Rotate PDF changes the stored attribute and hands you a new file; so does Organize pages, which is the better choice when different pages need turning different ways — a report with a few landscape tables in the middle, for instance.

Two things worth knowing:

• Rotation is lossless. Only a number changes. Nothing is re-encoded, no quality is lost, and the file size is essentially unchanged — unlike most edits to a page.
• It is per page. A document can have pages at four different rotations quite legitimately, and a tool that rotates everything at once will make the already-correct pages wrong.

Afterwards, confirm by reopening the saved file in a fresh window rather than the one you were working in, which may still be showing you a view rotation.

Rotation, printing and scanning

Printers read the stored attribute, not your screen. This is where a view rotation reveals itself: the page looks fine in front of you and comes out of the printer sideways, which is exactly the report described above.

Scanners are the usual source of the problem. A document fed in the wrong way round, or a scanner set to auto-rotate that guessed from the wrong cue, produces pages at 90 or 180 degrees — often only some pages, which is why mixed rotations are so common in scanned files.

If the pages are upside down rather than sideways, rotate by 180. It is easy to fix by eye and easy to miss when skimming a long file, so check the last page as well as the first.

When rotating does not help

A few situations look like a rotation problem and are not:

• The content itself was drawn sideways. Some generators place landscape content on a portrait page rather than setting the page size. Rotating then turns the page and the content together, and you are no better off. Crop or Resize is the tool for reshaping the page.
• The page is a mixture — an upright header with a sideways table. Nothing can fix that with one rotation, because the two want opposite answers.
• The rotation will not save. If the file is protected against modification you will need to remove that restriction first, and only where you are entitled to. What a PDF password protects explains the two different kinds.
• The file is damaged and tools refuse to write it. Repair PDF first, then rotate.