A scan can look straight in a thumbnail and still be a degree or two off. That is enough to make text fuzzy after OCR and to leave uneven margins when printed. Deskew rotates each page back to square without changing the page content.
Step by step
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1
Upload your PDF
Drag your PDF onto the box or click Choose file. It is sent over an encrypted connection and only used for this task.
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2
Set the options
Adjust only straighten strongly skewed pages, manual angle in degrees (blank = automatic) and only specific pages:. Every field has a sensible default, so you can usually run the tool straight away.
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3
Run it and download
Press Deskew and the page shows progress while it works. When it finishes you get a download link — nothing is emailed and nothing is stored longer than it needs to be.
Why scans skew
Paper feeds into a scanner at a slight angle, a phone is not held parallel to the page, or a book page curves near the spine. Automatic deskew estimates the text baseline and rotates the page; a manual angle is better when the page has little text or a strong graphic that confuses the estimate.
Automatic or manual, and which pages
Start with automatic detection. If only some pages are crooked, list those pages and leave the straight ones alone. “Only straighten strongly skewed pages” is a useful guard for a mixed batch: it avoids needlessly rotating pages that are already square. A manual angle is in degrees; positive and negative directions matter, so check one page before applying it to a whole run.
Check before OCR or printing
Open the deskewed PDF and look at a line of text at 100%. The page should read horizontally, with even margins on both sides. Straightening is usually the step before OCR; better baselines give recognition less work to do. If the page is still curved rather than tilted, deskew cannot flatten the curve — rescan or use a photo-correction workflow instead.
Good habits for Deskew
- The preview updates as you type, so you can judge spacing before running it.
- Leave a page range blank to apply to every page.
- Colours accept a hex value, so you can match an existing brand colour exactly.
Common questions
Is this tool free?
Yes. Every tool on this site is free to use, with no sign-up, no watermark and no daily task limit.
Why does this tool sometimes say a component is missing?
This feature relies on the optional fitz component. Everything else keeps working; an administrator can enable it on the server.
Do I need to install anything?
No. The tools run in your browser and are processed by this server.
What happens to my files?
They are stored under an unguessable id and swept automatically after a couple of hours. Nothing is shared or indexed.
Does it work on a phone?
Yes. The page pickers and editors are built for touch, so dragging, rotating and selecting pages all work without a mouse.
What does Deskew do exactly?
Automatically straighten and deskew scanned PDF pages.
Does deskew crop the page?
It rotates the page content. Some white corners may remain after a large correction; use Crop PDF afterwards if the margins need tidying.
Can I straighten only one page?
Yes. Use the pages field to apply deskew to the pages that are crooked and leave the rest untouched.
Does deskew improve OCR?
Usually. Straight text gives the recogniser cleaner baselines, especially on small print and tables.