Tool
Compress PDF
Reduce PDF file size (best-effort — image re-encoding and metadata cleanup).
Compress PDF Online: Reduce PDF File Size for Email and Upload
Large PDFs — especially ones full of scanned pages or high-resolution photos — bounce off email attachment limits, stall on slow uploads, and get rejected by portals that cap document size. ConvertBrio's PDF compressor re-encodes the images embedded in your document at a more efficient quality and resolution, and strips metadata the file doesn't need, so the same pages come back in a smaller file.
It's free, runs in your browser with no signup, and doesn't add a watermark. The compression is lossless for text and vector graphics — those stay perfectly sharp — and lossy only for embedded photos and scans, where a small, usually invisible quality reduction buys a large drop in file size.
How to use this tool
- 1
Upload the PDF
Drag your file into the box or browse for it. One PDF per run, up to 100 MB.
- 2
Click Compress
ConvertBrio finds the embedded JPEG images, re-encodes them at a lower quality, downsizes any that are larger than they need to be, and removes unused metadata.
- 3
Download and check the size
The compressed PDF downloads automatically. Open it to confirm the pages still look acceptable — if it's not small enough, see the tips below on scanned documents and splitting.
How PDF compression works
A PDF's size is almost always dominated by one thing: embedded raster images. Text, fonts, and vector drawings are tiny by comparison. So ConvertBrio's compressor focuses where the weight is — it locates the photographic images inside the file, re-encodes them with more efficient JPEG settings, and scales down any image whose resolution is far higher than a screen or printer could use.
Everything that isn't a photo is left untouched: paragraph text stays selectable and razor-sharp, vector logos and charts keep their crisp edges, and the page layout doesn't move. Document metadata that serves no functional purpose is dropped to reclaim a little more space.
Which PDFs shrink the most
The reduction you'll see depends entirely on what's making your file big in the first place.
| PDF type | Typical result |
|---|---|
| Scanned document (photos of pages) | Large reduction — often 40–70% smaller |
| Report with embedded photos or screenshots | Moderate reduction, varies with image count |
| Slide deck exported to PDF | Moderate reduction if slides carry photos |
| Text-only PDF (contract, ebook, invoice) | Little change — it's already compact |
| PDF whose images are PNG or CMYK | Limited — those image types are skipped to avoid colour damage |
Compressing a PDF without losing quality
For any PDF that's mostly text, compression is effectively lossless — you lose nothing visible. For scanned or image-heavy PDFs, the images are re-encoded, so there's a real but small quality trade-off. In practice a scanned page compressed with this tool still reads cleanly on screen and prints fine; the difference only shows if you zoom in hard on a photograph. If a document absolutely must keep original image fidelity, compress it and compare the result before deciding.
Getting a PDF under a specific size (100 KB, 500 KB, 2 MB)
This tool applies one efficient compression pass rather than iterating to an exact target, so it won't guarantee a precise kilobyte figure. But a few things move the needle when you have a hard limit:
If your PDF is a scanned document, it will usually drop dramatically in one pass — try it first. If it's still over, split it into fewer pages with the Split PDF tool and compress each part, or export the pages you actually need. If the bloat comes from one or two enormous photos, compressing those images separately with Compress Image (which does have an exact-size target) before rebuilding the PDF gives you the tightest control.
Compress vs split
Compression reduces the weight of each page. Splitting reduces the number of pages. If your 30 MB PDF is 300 text pages, compression won't help much — Split PDF into sections is the answer. If it's 10 scanned pages at 3 MB each, compression is exactly the right tool. They're complementary, and for a stubborn file it's normal to use both.
Privacy and limits
Your PDF is encrypted in transit, processed automatically on ConvertBrio's servers with no human review, and both the original and the compressed copy are deleted within 24 hours. One file per run, up to 100 MB, free, no account, no watermark.
Related Tools
Compress PDF — FAQ
Common questions about compressing PDF file size online.
How do I compress a PDF online for free?
Upload your document to ConvertBrio's Compress PDF tool and click Compress. It re-encodes embedded images and removes unnecessary metadata to shrink the file, which downloads automatically — no account, no watermark, no email required.
Can I compress a PDF without losing quality?
Text and vector content is never degraded — it stays perfectly sharp. Only embedded photos and scans are re-encoded, with a small quality reduction that is usually invisible at normal viewing size. Text-heavy PDFs compress with no visible loss at all.
How do I make a PDF smaller to email it?
Run it through this tool once. Most email limits are 20–25 MB; a compressed scanned document or photo-heavy report typically drops well under that. If it's still too large, split it into parts with Split PDF and send them separately.
Can I compress a PDF to exactly 100 KB or 300 KB?
This tool doesn't target an exact size — it applies one efficient pass. For strict limits, compress a scanned PDF here first, then reduce page count with Split PDF if needed, or compress the largest embedded images separately with Compress Image, which does support an exact KB target.
Why didn't my PDF get much smaller?
It's probably already compact — a PDF that's mostly text has very little to remove. Files with high-resolution scans or embedded photos see the biggest reductions. PDFs whose images use PNG or CMYK colour are also skipped, to avoid altering colours.
Does compressing change the page layout or text?
No. Page dimensions, text position, fonts, and selectable text are all preserved exactly. Only the file size changes.