I rotated a page 90 degrees and it came out upside down instead of upright. Why?
Because the tool adds your turn to the rotation value already stored in the page. A page saved at 90 plus 'Right 90°' becomes 180, which is upside down. The thumbnails show the final orientation before you export, so if one looks upside down, press 'Clear all rotation' and try the other direction.
The page was rotated before you touched it
Every page in a PDF carries a rotation value: 0, 90, 180 or 270. Your reader applies it when displaying, so you see the result and never the number. Scanners and phone scanning apps often save pages with a value other than zero. So a page that looks 'sideways' to you may really be stored at 90 and need another 270 to stand up, not another 90.
The Rotate PDF pages tool does not wipe the old value and put yours in its place. It adds the two together and takes off 360 if the total goes past a full turn. That protects any correct rotation already in the file, but it means the direction that 'looks' right is not always the right one.
A page stored at 90, and you add 'Right 90°': the new value is 180, and the page is upside down.
The same page with 'Left 90°', which is 270 clockwise: the new value is 0, and the page is upright.
A page stored at 0 with 'Right 90°': the new value is 90, as you would expect.
Do not guess: the thumbnails show the result
The thumbnails in the tool do not just show the page as it is, but as it will be after export. Each press of a rotation button turns the thumbnail at once and puts a badge on it with the added angle, such as +90°. If the thumbnail is upside down after your press, the exported file will be upside down exactly the same way. Do not download until it looks upright.
If the page came out upside down, three ways to fix it
- Press '180°' on the same page: the added 90 plus 180 makes 270 added, which is the same as 'Left 90°'.
- Or press 'Left 90°' twice: the first press cancels your turn, the second turns the page the right way.
- Or press 'Clear all rotation' to put every page back to its original orientation, then start with the other direction.
What if you downloaded before noticing?
Your original file has not changed, so go back to it and start again. If all you have is the rotated file, open it in the tool and add '180°' to the upside-down page. The tool reads its new value of 180 and adds 180, which brings it back to 0.
Common questions
Why does the tool add the angle instead of replacing it?
Because adding protects what is already right in the file. Replacing would spoil every landscape page that was rotated on purpose whenever you turn the whole file.
How do I find out a page's stored value?
You do not need to. Look at the thumbnail: it shows the page with the old value and your turn applied together.