PDFSizeFit
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Under the hood

How PDFSizeFit Works

Most PDF compressors ask you to pick a vague quality level ("low," "medium," "high") and hope the result is small enough. PDFSizeFit works backward from the number you need: you set a maximum size, and the tool tries to hit it.

The short version

Five steps, all in your browser

Every tool on the site follows the same flow. Compression adds a search for the right quality level in step three.

  1. Choose your PDF

    Your browser reads the file into its own memory. There's no upload step.

  2. Pick a target or a task

    A size limit for compression, or pages and order for the other tools.

  3. Processing on your device

    The work runs in a background thread in your browser tab, so the page doesn't freeze.

  4. Check the result

    For compression, the size shown is measured from the file you'll get, not estimated.

  5. Download

    Your browser saves the new file. The original is never changed.

Compression in detail

What happens when you click "Compress"

  • Check whether compression is needed

    Every file

    The file is checked as a real, readable PDF first. If it's already at or under your target, the tool stops there and says so.

  • Repack the file and re-encode images

    Every attempt

    Each attempt drops unused objects, rebuilds the file's structure, recompresses its data streams, and re-encodes images as JPEG. The tool tries several quality levels and keeps the highest one that reaches your target. A PDF with no images is only repacked, so its pages look exactly the same.

  • Turn pages into images, only as a last resort

    Last resort

    If the target still isn't reachable and the file is image- or scan-heavy, pages are converted to compressed images. This is the one step that gives up selectable text, and the result screen tells you when it happened.

Privacy

Your PDF stays on your device

The website loads from our server like any other. Your PDF doesn't go back to it.

  • No upload step

    Your file opens in the browser tab and is compressed there, by code that downloaded with the page.

  • Enforced in the code

    The page's security policy only lets it connect to this site, and an automated test fails if the PDF code tries to make a network request.

  • Gone when you close the tab

    Files are held in memory only. The site saves two small settings in your browser: your theme and your last target size.

  • No account

    There's nothing to sign up for, so there's no account to tie a file to.

Check it yourself: open your browser's developer tools, switch to the Network tab, and compress a file. You'll see requests only for the site's own files, and none carrying your document.

Read the privacy policy

Try it on your own PDF

Pick a size, and see the measured result before you download anything.

Compress a PDF