How to Deskew a Scanned PDF (Straighten Crooked Pages)
Written and fact-checked by The EditPDF AI Team
A "skewed" scan is one where the page content sits at a slight angle instead of running straight — usually from the paper shifting slightly on a flatbed or being photographed off-axis. Deskewing rotates the content back to level before you save the file.
Why does a scanned page come out crooked?
Skew almost always comes from the capture step, not the document itself — the paper wasn't perfectly aligned against a flatbed's edge, or a phone camera wasn't held exactly parallel to the page. Even a couple of degrees of tilt is enough to visibly slant every line of text.
- ·Flatbed scanners: paper nudged slightly off the edge guide
- ·Phone/camera capture: the camera angle wasn't perfectly overhead
- ·Bound documents: pages near the spine curve rather than sit flat
How to straighten a page as you scan
- 1Open Scan to PDF and use your phone or webcam camera to capture the page.
- 2The tool detects the page edges and straightens the perspective automatically as part of capture — no manual rotation needed for typical skew.
- 3Review the straightened result before saving; recapture the page if the edge detection missed a corner (common with a page that blends into the background).
Scan to PDF's auto-straightening applies during capture, not to an existing image or PDF you already have. For an existing file, re-scanning the physical page is currently the more reliable fix than trying to correct an already-flattened scan.
Getting a straighter scan in the first place
- ·Keep the camera or scanner lid as parallel to the page as you can manage before capturing
- ·Make sure all four page edges are visible and contrast clearly against the background — edge detection needs a clean boundary to straighten against
- ·For bound documents, press the spine as flat as the binding allows before capturing that page
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