Skip to main content
Mofumi PDF

Deskew PDF

Beta

Automatically straighten crooked scanned pages.

100% Private — files never leave your device
Upload PDFDrop files here or click to chooseAccepted: PDF Files never leave your device

About this tool

Pages fed into a scanner at a slight angle are hard to read, look unprofessional and confuse OCR. Deskew PDF measures how much each page is tilted and rotates it back so the lines of text run level.

The angle is found with a projection-profile method: the page is rendered at low resolution and tested at many small angles; text lines line up most sharply at the true skew. Pages are then rotated as vectors, so any existing text layer stays selectable, and the page keeps its original size.

Blank pages and pages that are already straight are left alone. The report lists the angle detected on every page. This tool is in beta: pages with very little text, or with mostly pictures, may not be detected reliably — use Manual Deskew for those.

Engines: pdfjs · canvas · pdf-lib

How to use

  1. 1

    Drop a scanned PDF.

  2. 2

    Optionally adjust the sensitivity and the largest angle to look for.

  3. 3

    Click Deskew PDF and check the report for the angle applied to each page.

Use cases

  • Scanned paperwork

    Straighten invoices, receipts and forms fed through an office scanner.

  • Before OCR

    Text recognition is far more accurate on level lines — deskew first, then run OCR.

  • Book scans

    Correct the small tilt from phone scans or flatbed captures of book pages.

Frequently asked questions

How large an angle can it fix?

Up to 20° (10° by default). Larger tilts are rare and usually need a 90° rotation instead.

Does it lose quality?

No re-compression happens: the page is rotated as a whole, so images keep their original quality.

What does sensitivity do?

Low only corrects clearly crooked pages (0.5° or more), High also fixes very small tilts.

You may also like