PDF Compressor
Optimize a PDF file in your browser and download a cleaned copy. Useful for reducing overhead, rebuilding file structure, and preparing PDFs for sharing.
Input
Drop a PDF here
or click to browse
Settings
This optimizer rebuilds the PDF with compressed object streams and removes editable metadata. It does not rasterize pages, so text and vectors remain selectable.
How to optimize a PDF's file size
Load a PDF, optimize it, and compare the sizes before you download the new copy.
- 01
Load the PDF
Drop it in or browse. The file is read in your browser, so confidential documents stay on your device.
- 02
Optimize it
The tool rewrites the file's structure, clears the title, author, subject and keywords fields, and saves a new copy. Text, images and pages are untouched.
- 03
Compare the sizes before you download
You'll see the original size, the new size and the percentage saved. If the saving is small, see the table below for what will actually make the file smaller.
What this optimizer does, and why savings are modest
This is lossless optimization, not image compression. It opens the PDF with pdf-lib and saves it again using object streams, a more compact way of storing the file's internal objects that was added in PDF 1.5. It also blanks some metadata fields. Nothing visible changes: text stays selectable and every image keeps its original pixels.
So the savings depend on how much of the file is structure rather than content. We ran it on six real PDFs: Apple's licence documents and Xcode's acknowledgements, 231 to 310 pages each, mostly text. They shrank by 7.6% to 10.3%, for example from 2,838 KB to 2,621 KB. For a scan or a photo-heavy brochure, where images make up nearly all of the size, expect little or no saving.
What actually shrinks a big PDF
If this tool doesn't get you under an upload limit, the size is almost certainly coming from images. Here's what to try, in order of effort:
| Approach | Typical effect | Quality cost |
|---|---|---|
| This optimizer | Small savings, around 5–10% on text-heavy files | None |
| Re-export from the source app with a smaller image setting | Large, often several times smaller | Images slightly softer |
| Mac Preview: File › Export › Quartz Filter › Reduce File Size | Large, especially for scans | Can be heavy-handed on photos |
| Resize photos before building the PDF | Large, roughly in proportion to pixels removed | Depends on the new size |
| Split out only the pages you need | In proportion to pages removed | None |
For PDFs you build from photos, the easiest fix is upstream. Resize the images to around 1,600 px wide with the Image Resizer, then put them into a PDF with Image to PDF.
When lossless optimization is enough
Trimming a text-heavy report
Long reports exported from older tools often carry bulky internal structure. A lossless re-save can take a few hundred kilobytes off.
Clearing document properties
The title, author, subject and keywords fields are blanked, which removes a name or working title you might not want to share.
Optimizing without uploading
Contracts and statements can be processed without sending them to an online compressor's servers.
Worked example: a 12 MB scan and a 5 MB limit
Say you scanned a 12-page document at 300 DPI and the PDF is 12 MB, about 1 MB a page. Every page is a photo, so this optimizer will save almost nothing. An A4 page at 300 DPI is roughly 2,480 × 3,508 pixels.
Rescan or re-export at 150 DPI instead and each page becomes about 1,240 × 1,754 pixels. That's half the width and half the height, so a quarter of the pixels, and the file drops to roughly 3 MB. Text at 150 DPI is still easy to read on screen and prints cleanly enough for forms and letters. Most scanner apps have a resolution or quality setting; it's the single biggest lever on a scanned PDF's size.