How to Fix a Blurry PDF and Make It Clearer

Short answer: to fix a blurry PDF, open Improve PDF Quality, choose the file, compare the Before and After preview, and start the upscale. An AI model in your browser rebuilds the pictures inside the PDF at two or four times their resolution, for free and without uploading anything. That helps a low-resolution scan. It cannot rescue a page shot out of focus, and it can reshape very small print.

Which kind of blurry do you have?

Zoom to 400% and look closely at a line of words. What you see decides the fix.

Blocky, stair-stepped letters. The page is a low-resolution picture, usually a scan or a screenshot. This is the case the tool was built for.
Smeared letters, as if the camera moved. The detail never reached the file, so you need a new scan or photo.
Crisp at 400%, soft at normal size. The file is fine, and the softness comes from how the viewer draws the page. Try another PDF viewer, or print one page to check.
Sharp but pale. That is a faded scan, not a blurry one. Darken PDF makes the ink darker.

How to make a PDF clearer

Open the tool and choose your PDF.
Wait for Looking for pictures to finish. The page tells you how many pictures it will upscale and why it leaves the others alone.
Under How much larger, keep 2x (recommended).
Check Preview of one picture. The first run downloads the AI model. Under the preview, the page says how long the whole PDF will take on your device.
Press the button that shows the picture count, for example Upscale 12 pictures.
Read the two file sizes, then press Download PDF. Try Another Setting goes back with the same file.

2x or 4x: one example

Take a US Letter page scanned at 150 DPI, about 1275 by 1650 pixels. 2x takes it to 300 DPI, where the tool itself treats a picture as sharp enough to print. 4x adds nothing here: the result would pass about 16 megapixels, the most the tool writes, so the page gets 2x anyway.

4x pays off on rougher scans. The same page at 100 DPI can take it, at the cost of a much bigger file.

Check small print by eye

AI adds detail it cannot know for sure. In our tests, text of normal size stayed correct, while letters around 10 pixels tall were sometimes reshaped. So a result can look crisp and still be wrong. Compare account numbers, dollar amounts and policy numbers against the original.

If someone else will rely on the document, such as a W-2, a lease or an insurance claim form, do not upscale it. Ask the issuer for a fresh copy, or scan the paper again.

When this will not help

The page is high resolution but out of focus. The tool measures resolution, not focus. A picture printed at 300 DPI or finer is listed under Already sharp enough to print and left alone, however soft it looks. Scan the page again at 300 DPI, or take a new photo in good light and use JPG to PDF.
It is a fax or a pure black-and-white scan. These are left alone by default. If the page offers Also upscale black-and-white scans, check that box: edges get smoother and the file grows.
It came out of Word with coarse pictures. In Word for Windows, the Minimum size option under Save As PDF shrinks pictures on export. Go back to the document and save it again with Standard. Other versions of Word may name these options differently.
It was compressed too hard. Find the version from before compression. It holds real detail that AI can only imitate.

Frequently asked questions

Why does my PDF look blurry when I zoom in?

The page is a picture with a fixed number of pixels, so zooming spreads them out. Real text is stored as shapes and stays crisp at any zoom.

How do I make a scanned PDF clearer for printing?

Run it at 2x and print one page before you print the rest. The pages keep their size, so a Letter page stays Letter, and only the resolution of the pictures goes up.

Will my PDF stay searchable?

Text you could select before stays selectable and links keep working, because only the pictures are replaced. A scan with no text layer stays that way, so run the result through OCR Scanner if you need to search it.

Why did my PDF get bigger?

A picture upscaled 2x has four times as many pixels, and 4x has sixteen times as many. If the file is too large for an email or an upload form, choose 2x or run the result through Compress PDF.