Upside-down pages, fixed without looking for them
Phone scanning apps, document feeders and copiers all produce the odd upside-down or sideways page, and in a 30-page scan they’re easy to miss until the reader finds them. Drop the PDF here and every page is checked. The ones that aren’t upright are turned before you’ve done anything, and a note lists them: “Pages 4 and 11 were upside down and are turned upright.”
You see every page in the preview before saving. Tap any page to turn it further if we got one wrong or missed one. Then press Save upright PDF.
How we can tell which way is up
Pages with real text (made on a computer, not scanned) are easy. The file says which way each line of text runs, so the answer is exact, in any language.
Scans are pictures of pages, so we read the picture. Three things are checked:
- Which way the lines run. Lines of text leave thin white gaps between them. We look for those gaps across and down the page, after straightening a crooked scan by up to 6°.
- Which side the letters reach out from. In English and many other scripts, more letters stick up (b, d, h, k, l) than hang down (g, p, y). Upside down, that flips.
- Which edge the lines start at. Lines start flush on the left and end ragged on the right. Upside down, the flush edge moves to the right.
A scanned page is turned only when the second and third checks agree. Then the whole document is checked as one: real documents are almost all upright, so if the checks say most pages are upside down, we trust them less, not more. A single page judged from its picture alone is offered as a “maybe” and not applied.
When we leave a page alone
We don’t turn a page unless we’re sure, because a wrong turn is worse than none. You’ll see pages left as they are when they are:
- photos, drawings or diagrams with little text;
- tables of mostly numbers and lines;
- in a script the picture checks don’t fit. Hindi and other scripts with a line along the top, Arabic and Hebrew often give mixed answers, so we leave those for you to turn with a tap.
Afterwards
The rotation is saved in the file, so the pages open upright everywhere. Scans with upside-down pages often have empty backs too: Remove blank pages finds those. To turn pages yourself without anything automatic, use Rotate PDF.
Checked against the tool on 22 October 2026. How we write and test these guides