Compress PDF files

How to Compress PDF

1

Add your PDFs

Click “Select files” or drag and drop one or more PDFs. Batch compression is supported — every file is compressed on its own and reported separately.

2

Pick a level or a target

Recommended balances quality and size for most documents; Extreme goes as small as the presets allow. Or set a Target size (100KB–1MB) — the target then owns the quality decision and the level cards grey out.

3

Compress and download

Click “Compress”. Each file processes in your browser and the result list shows its size before and after, so you can verify the fit before uploading it anywhere.

Every step runs in your browser. No server uploads, no waiting.

Why use this tool

DukPdf’s Compress PDF tool reduces the file size of your PDFs without re-rendering pages or deleting content. It runs a Rust compression engine compiled to WebAssembly inside your browser: images are downsampled and re-encoded, embedded fonts are subset to the glyphs actually used, and the file’s internal structure is rewritten compactly. Text is never rasterized — it stays selectable text at any setting. Pick Recommended for a balanced pass or Extreme for the smallest file, and if compression would somehow make your file larger, you get the original back unchanged — never a “compressed” file bigger than the input. If a form gives you an exact limit, target it directly: 100KB, 200KB, 300KB, 500KB or 1MB — each page opens with that whole-file target preselected and searches for the best quality that fits it. If you need to combine several compressed files, use Merge PDF. To add a password to the compressed result, use Protect PDF. For a deeper guide covering lossy vs lossless compression, see our compress PDF guide.

When you'd use this

Email attachment limits

Shrink a PDF that’s too large for Gmail (25MB), Outlook (20MB), or a corporate mail server — without uploading the document anywhere.

Upload form size caps

Reduce a scanned PDF to fit a portal that caps uploads at 5MB or 10MB. Quality stays readable.

Archive storage

Cut long-term storage costs by compressing old reports, contracts, and tax documents before archiving.

Faster page loads

Compress product catalogs, manuals, and ebooks embedded in your website so they open quickly for visitors.

Why this matters for your privacy

☁️ CLOUD PDF TOOLS
📄 your-file.pdf
↓ uploaded over the internet
☁️ their server

A copy of your document sits on someone else’s infrastructure — deleted on their schedule, not yours.

✗ OUT OF YOUR HANDS
DukPdf
📄 your-file.pdf
⟳ stays right where it is
💻 your device

Processed by your own browser, start to finish — on your machine, under your control.

✓ STAYS ON YOUR DEVICE

We send the software to your file — not your file to our servers.

Compress PDF — questions

How much can I shrink a PDF?

It depends entirely on what is inside. Scanned and image-heavy PDFs compress hardest — reductions of 80–90% are common because the images carry almost all the bytes. Text-only documents start small and shrink modestly. A PDF built from already tightly-compressed photographs may barely move; the before-and-after sizes in the result list tell you exactly what happened.

What is the difference between Recommended and Extreme?

Recommended downsamples oversized images to 150 DPI — ebook quality — and leaves well-sized photos’ encoding alone. Extreme targets 72 DPI screen quality, re-encodes every image, and strips optional metadata. Both subset fonts and rewrite structure; neither touches your text.

How does compressing to an exact size work?

Pick a target in the size row (or start from a preset page like Compress PDF to 200KB) and the engine runs a top-down search over its quality ladder, keeping the best version that measures at or under the limit. The target applies per file — a batch gives you one under-limit file per input.

Will compression reduce image quality?

Recommended only reduces images that exceed ebook resolution, which most screens cannot show anyway. Extreme and tight size targets visibly reduce photographs and scans — that is the trade they exist to make. Text and vector content stay sharp at every setting because they are never rasterized.

Can I compress password-protected PDFs?

Yes. You’ll be prompted for the password before compression starts. The compressed file is saved without the password — add one with Protect PDF if needed.

Are my files uploaded during compression?

No. Compression runs entirely in your browser via a Rust engine compiled to WebAssembly. Open DevTools → Network tab while compressing — zero upload requests carry your document.

Why did my PDF barely shrink?

It was probably already optimized: photographs stored at sensible resolution with efficient encoding leave little to reclaim. DukPdf also guarantees the output is never larger than the input — when nothing can be saved, you get your original bytes back rather than a file that quietly grew.

Is there a file size limit?

The web app accepts files up to 200MB each (600MB per batch) to protect your browser’s memory. For anything bigger, the free desktop app has no size limits.

Tools that pair with compress pdf

→ Merge PDFCombine multiple compressed files→ Protect PDFPassword-protect after compressing→ Edit MetadataStrip authoring metadata to shrink further→ OCR PDFMake scanned PDFs searchable first→ Split PDFExtract and compress specific pages→ Remove PagesDrop pages to reduce size further

Compress PDF for a specific size

→ Compress PDF to 200KBThe most common upload cap on the web. Government portals, university forms and job sites …→ Compress PDF to 100KBThe strictest cap in common use. Exam registrations and legacy e-forms ask for 100KB when …→ Compress PDF to 500KBThe comfortable ceiling. 500KB fits generous portal limits and keeps multi-page scans look…→ Compress PDF to 1MBThe round number attachment fields ask for. CMS uploads, application systems and shared dr…→ Compress PDF to 300KBThe middle rung. E-tender portals and application systems that find 200KB too harsh settle…

Compress PDF guides

→ Compress PDF for emailCompress PDF for email free — fit Gmail (25MB) and Outlook (20MB) attachment limits. No se…→ Compress PDF online freeCompress PDF online free with no server uploads, no watermark. Shrink PDFs in your browser…→ Compress a PDF without uploading itReduce your PDF file size without uploading it anywhere. Compression runs in your browser,…
🔒 DukPdf — YOUR FILES NEVER LEAVE YOUR DEVICE

Ready to compress pdf? Your files stay yours.

No server uploads. No watermark. Just open a tool, drop your files, and download the result. Your original files are never modified.

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