How to straighten a crooked PDF scan: a step-by-step guide

Bijgewerkt op 2 oktober 2026

Deze handleiding is nog niet in het Nederlands beschikbaar en wordt daarom in het Engels getoond. De tool zelf werkt in het Nederlands.

A sheet that slid in the feeder comes out a degree or two crooked - harder to read, and lines that a search or a printout handles worse. Straighten PDF (Deskew) measures how much every page is tilted as the file loads and levels each by its own angle. You check the result on the thumbnails before anything is saved. It all happens in your browser; the scan is never uploaded.

Gratis te proberen, zonder account: je bestanden verlaten je apparaat nooit.

PDF rechtzetten (scheve scan corrigeren) openen

In het kort

  1. Drop your scanned PDFs on the page, or press Add files.
  2. Wait a moment while each page's tilt is measured - the thumbnails then show the pages levelled.
  3. Set an angle by hand on any page that needs it.
  4. Press Straighten pages: the levelled file is saved to your device straight away.

Add the scans

Drop the PDFs anywhere on the page, or press Add files. Every page's text lines are measured on arrival - the file list says how many pages of each file are tilted. The thumbnails show the pages as they will come out, already levelled, and a badge on each tilted page gives the angle it turns by.

Straighten PDF with three files: the crooked scan's first two pages carry -2.4° and 1.6° badges, the file list says 2 pages tilted
The badge says how much a page turns; the thumbnails already show the levelled pages.

Tilts up to 15° either way are found. A page with no text, almost no ink or a full-page photo is left as it is - there is nothing to measure on it.

Set an angle by hand

Every page is chosen to begin with; click or drag on the thumbnails to narrow it down, or use the bar above them (odd, even, every Nth, page numbers). Then Set an angle by hand turns the chosen pages to the angle shown, in tenths of a degree, positive clockwise - the thumbnails follow with every step. Measure again reads the pages anew, and Reset at the top of the options goes back to what was measured.

The rail: 2 pages tilted, Measure again, the angle stepper at -2.4°, and Keep the page size switched on

Keep the page size (on by default) keeps an A4 an A4: the turned content is scaled down a touch so its corners stay on the page. Switch it off and the page grows a little to hold the turned content at full size.

Straighten and save

Press Straighten pages. The line under the button counts the pages that turn. The file is saved to your device at once - several files together as a ZIP. The scan isn't re-compressed: the page is turned as it is, so the picture loses nothing, and bookmarks and links stay with their pages.

Straighten before OCR - make a PDF searchable: level lines are read more accurately.

Several files at once

Every file is measured on its own, so a stack of scans is levelled page by page in one run. Under All files in Apply to, a hand-set angle becomes one rule for the chosen pages of every file; leave it empty and each page turns by what was measured on it.

Limits

Without an account, and with a free one, you can straighten two files in a run, each up to 15 MB. With Pro there is no limit on the number or the size.

What next?

Klaar om het te proberen?

Gratis te proberen, zonder account: je bestanden verlaten je apparaat nooit.

PDF rechtzetten (scheve scan corrigeren) openen

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