Compress PDF without losing quality
Reduce PDF file size for email, web, or storage. Choose recommended (best balance), high (smallest), or low (best quality). Powered by Ghostscript with content-aware downsampling.
Drag & drop a file
or browse from your computer · max 100 MB
Compressing a PDF is the fastest way to fit a document under an email size limit, speed up uploads to forms with tight caps, or save storage on a device. PDFOnly's PDF compressor uses Ghostscript with content-aware downsampling — it keeps text crisp at full resolution and selectively shrinks embedded images. The result: typical documents reduce by 60-85% with no visible quality loss in normal viewing. For PDFs full of high-resolution photos, savings can be even higher.
How to compress pdf step by step
- 1
Upload your PDF
Drop your file or click to browse. We accept any standard PDF (including scanned, password-protected, encrypted with a known password). Max 100 MB free, 200 MB on Pro.
- 2
Pick a compression level
Three presets. 'Low' uses 300 DPI image downsampling — best for documents going to print. 'Recommended' uses 150 DPI — balanced for screen reading and email. 'High' uses 72 DPI — smallest file, best for web preview only.
- 3
Click Compress and wait a few seconds
Compression uses Ghostscript on a dedicated worker. A 50-page document typically compresses in under three seconds. Larger PDFs scale linearly — 500 pages takes ~30 seconds.
- 4
Download and verify
The result downloads as a single compressed PDF. Open it to verify text is still sharp and images are acceptable for your use case. If quality dropped too much, re-run with a less aggressive level.
Why compress pdf on PDFOnly
Content-aware compression
We don't just slap a quality flag on the whole file. Text glyphs are kept at full fidelity, fonts are subset to only the characters used, and images are downsampled separately based on their original resolution.
True PDF/A preservation
Compression keeps your PDF compliant with PDF/A archival standards (when the input was PDF/A). Most online tools strip metadata and break archival compliance silently.
Visible feedback on size savings
We show before/after file sizes and percentage reduction so you know exactly what you saved. Helpful when you're comparing presets to find the right balance.
Privacy by default
Files are processed in isolated workers, deleted within an hour, and never used for AI training or analytics. Compression happens on our servers, not in third-party APIs.
What people use compress pdf for
A few common scenarios. If your workflow looks like one of these, this tool is a good fit.
Fit a PDF under a 1 MB email cap
Many corporate mail filters and government portals reject attachments larger than 1 MB. Use the High compression preset to bring most documents under the limit in a single click.
Speed up uploads to slow connections
Cellular and rural broadband often top out at 1-5 Mbps upload. Compressing before upload turns a 60 MB report into 6 MB and saves 10× the wait time.
Save storage on legal e-discovery archives
Law firms holding 10-100 GB of case documents save real disk space by running their archive through compression. The archived content is still searchable and printable.
Make scans web-ready
Mobile-scanned PDFs are typically 10-50× larger than necessary because the camera captures at 300+ DPI. Recommended compression brings them down to a sensible web size.
Reduce page-load time for embedded PDFs
If you embed PDF brochures or whitepapers on a marketing site, smaller files mean faster Time-to-Interactive and better Core Web Vitals scores.
What you get
- Three compression levels: Low (best quality), Recommended (balanced), High (smallest size)
- Average size reduction: 60-85% on text-heavy documents, up to 95% on image-heavy ones
- Text stays sharp at every level — only images are downsampled
- Subset and de-duplicate fonts automatically — saves space without breaking display
- Detect and merge identical images across pages — common in long reports
- Output PDF/A compatible — long-term archival quality preserved
- No watermarks, no signup required for files under 100 MB
Frequently asked questions
How much can I expect to shrink my PDF?
Text-heavy documents (contracts, reports, manuscripts) typically reduce 40-70%. Image-heavy or scanned documents can reduce 80-95%. PDFs that are already heavily optimized may only shrink 5-15% — there's a floor on compressibility once content is already efficiently encoded.
Will my PDF look worse after compression?
On 'Recommended' (150 DPI), most readers can't tell the difference at normal zoom levels. 'High' (72 DPI) is suitable for web viewing but you'll see blurry images if you zoom in. 'Low' (300 DPI) is essentially indistinguishable from the original even at 200% zoom.
Will compression break my PDF's text searchability?
No — text remains fully searchable, selectable, and copyable. Compression only affects how images are encoded and downsampled. The text layer is preserved at original quality regardless of preset.
Can I compress a scanned PDF?
Yes, but for best results run it through our OCR PDF tool first. OCR adds a searchable text layer over the scanned images, then compression can shrink the underlying images aggressively without affecting the text. The combined result is searchable AND small.
What's the difference between compression and optimization?
'Compression' usually means making the file smaller. 'Optimization' includes that plus structure changes (linearization for fast web view, removing unused objects, subsetting fonts). Our compressor does both — your output is also linearized for streaming display.
Can I compress a PDF without re-uploading every time?
Pro plans include API access — POST your PDF to our /v1/compress endpoint and get back a compressed version programmatically. Useful for batch jobs or automated pipelines.
Why didn't my PDF shrink much?
Likely already optimized — perhaps it was previously compressed, exported from a tool that auto-optimizes, or contains mostly vector graphics (which compress well already). Try the 'High' preset, or check our PDF audit feature in Pro to see exactly what's taking up space.
Ready to compress pdf?
Free to use for the basics. Files are auto-deleted within an hour and never used to train AI.
Open Compress PDF