Rotate PDF pages and save them that way

What this tool does

The tool shows a small picture of every page. You turn single pages by pressing them, or all pages at once, and save a new PDF in which the pages open the way you turned them, in every PDF reader.

Only the rotation changes. Text, pictures, links, bookmarks, form fields and document properties stay as they are, and nothing is compressed again.

How to use it

1. Choose a PDF, or drop it on the marked area. A picture of each page appears.
2. Press a page to turn it 90° clockwise. Press it again for 180° and 270°; a fourth press turns it back.
3. Or use Turn all left, Turn all right or Turn all upside down for the whole document. Undo all turns starts again.
4. Press Save rotated PDF and download the file. Its name ends in -rotated.

Each page is a button: with a keyboard, move to it with the Tab key and press Enter or Space. Its name says how far it is turned.

How the rotation is stored

Every PDF page has a rotation entry, /Rotate, which tells readers to turn the page by a multiple of 90° clockwise when they show or print it (ISO 32000-1, section 7.7.3.3). The tool adds your turn to that entry: a page that was already stored with 270° and is turned by 180° gets 90°, because 270 + 180 = 450 and 450 − 360 = 90.

The content of the page is not redrawn, so text stays selectable and pictures keep their quality. That is also why the rotation is permanent: it is part of the file, not a view setting of one reader.

The file is written again by pdf-lib. It usually comes out a little smaller or larger than the original, because objects are stored in a more compact way; the pages themselves are unchanged.

Worked example

A licence agreement of 310 pages and 2,896,912 bytes was opened in Chrome. The previews of the first pages appeared at once; the others are drawn when you scroll to them.

Turning only page 1 by 90° and saving took about a third of a second and gave a file of 2,675,295 bytes: page 1 now has /Rotate 90, the other 309 pages still 0. Turning all pages upside down gave 2,675,579 bytes, with /Rotate 180 on every page. The files are about 7.6% smaller than the original only because pdf-lib stores the objects more compactly.

Common mistakes

• Turning a page that only looks sideways in one app. Some apps remember a rotation for the view only; open the PDF in another reader first to see how it is stored.
• Pressing a page three times to turn it left. That works, but Turn all left is quicker when every page needs the same turn.
• Expecting a crooked scan to become straight. The tool turns by whole quarter turns only; it does not straighten a page that is a few degrees off.
• Opening a password-protected PDF. It cannot be read; remove the protection first with a program that knows the password.