How much smaller will it be?

Depends on content. Image-heavy PDFs (photos, scanned documents): 50-85% reduction. Mixed text+image: 30-50% reduction. Text-only PDFs: 5-15% reduction (text is already efficient). Already-compressed PDFs (passed through compression once before): 10-20% additional reduction. Try medium quality first — it's usually the right balance for screen reading.

At high-quality (300 DPI / 85 JPEG quality), virtually no visible degradation for screen reading and most printing. At medium (200 DPI / 75), screen quality is fine; small text in images may show slight artifacts. At low (150 DPI / 65), suitable for email-only sharing where the recipient just needs to read; not for print. Always preview the result on the target device (phone, computer, printer) before deploying.

Why did my text-only PDF barely shrink?

Text in PDFs is stored as vector data (font references + positioning), which is already extremely efficient — compression has nothing to optimize. The bulk of file size in image-heavy PDFs is image data. If your PDF is 10MB and almost all text, it likely has duplicate fonts embedded or accumulated revision history. Try a tool like Adobe Acrobat's “Reduce File Size” that strips redundant fonts and edit history.

An ISO standard for long-term archival PDFs (PDF/A-1, A-2, A-3). PDF/A files embed all fonts, prohibit certain features (encryption, JavaScript), and standardize compression to ensure files are renderable decades from now. Aggressive compression can break PDF/A compliance. If your document needs to comply with PDF/A (legal records, government archives), use a tool that specifically supports compressed PDF/A output.

Can I split a large PDF instead?

Yes, often a better solution. If your PDF is 50MB because it's 200 pages, splitting into 4 smaller PDFs (50 pages each, ~12MB each) lets you email them separately. Use the PDF-split tool. For sharing the original whole document, use a cloud drive (Drive, Dropbox, OneDrive) link instead of attaching — virtually unlimited size, recipients can preview without downloading.

What about online PDF compression services?

Many exist (Smallpdf, ILovePDF, Adobe Acrobat online). Trade-off: convenient but uploads your file to their servers. For confidential documents (contracts, medical records, financial statements), browser-based local compression is essential. Their free tiers also limit file size and number of compressions per day. For pure convenience on non-sensitive docs, online tools are fine; for anything sensitive, use local-only tools.

File & Format Converters · Free tool

Compress PDF

Reduce PDF size by downsampling embedded images and stripping unused objects. Runs in-browser — your file never leaves.

Updated June 2026

Drop a file or click to choose

Compress PDF by re-encoding pages as JPEG.

JPEG quality (60%)Resolution scale (1.00x)

Heavy compression works best for PDFs that are mostly images or scans. Text-heavy PDFs may lose selectable text.

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What it does

PDF file sizes balloon when documents contain high-resolution images, embedded fonts, scanned pages at high DPI, or accumulated incremental edits. A 200-page slide-deck PDF can easily exceed 50MB; an image-heavy report can hit 100MB+. These sizes hit email attachment limits (Gmail 25MB, Outlook 20MB, most enterprise email 25-50MB), slow uploads, and become unwieldy for sharing. PDF compression reduces file size through three main mechanisms: image downsampling (high-res images reduced to a target DPI — typically 150-300 for screen reading, 600 for print), image re-encoding (compress embedded JPEGs at lower quality, convert PNGs to JPEGs where appropriate), and object cleanup (remove unused objects, orphaned references, accumulated edit history).

The compressor takes your PDF and target quality level (high-quality / medium / low / ebook), and outputs a smaller PDF using pdf-lib + browser-side transformations. Typical results: high- quality (DPI 300, JPEG quality 85) — 30- 50% size reduction. Medium (DPI 200, quality 75) — 50-70% reduction. Low / ebook (DPI 150, quality 65) — 70-85% reduction. The tradeoff is image quality: high-quality preserves print-ready output; medium is fine for screen reading; low is for email-only or web preview where small text and image detail aren't critical. A 30MB report at medium compression typically becomes 10-15MB — fits in any email attachment limit.

Important caveats: (1) PDF compression is lossy for image-heavy PDFs — you can't undo it without going back to the original. Always keep your master copy. (2) Text-only PDFs compress poorly because text is already efficient (vector). Most compression gains come from images. (3) Already- compressed PDFs (those that have been through compression once) compress less in subsequent passes — diminishing returns. (4) Some PDFs have specific format requirements (PDF/A for archival, PDF/X for print) that aggressive compression may break. (5) Form fields and signatures may be affected; test critical PDFs before deploying. All processing runs locally; the file never uploads, important for sensitive documents.

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Paste this snippet into any page. Loads on-demand (lazy), no tracking scripts, and sized to most dashboards. Replace the height to fit your layout.

<iframe src="https://freetoolarena.com/embed/pdf-compress" width="100%" height="720" frameborder="0" loading="lazy" title="Compress PDF" style="border:1px solid #e2e8f0;border-radius:12px;max-width:720px;"></iframe>

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How to use it

Drop your PDF or click to browse.
Pick target quality: high-quality (print-ready), medium (screen-ready), low (email-only).
Click Compress — see size reduction percentage.
Preview the result to check quality is acceptable.
Download the compressed version; keep the original as backup.

When to use this tool

Email attachments — most clients limit attachments to 20-25MB.
Web upload limits — many forms cap PDF size at 5-10MB.
Document archives — reducing storage cost on cloud drives.
Sharing via Slack / messaging — many platforms limit to 5-10MB.
Mobile sharing — small files transfer faster on cellular.

When not to use it

Print-ready files where image quality is critical — high-quality compression only, or no compression.
PDF/A archival format — aggressive compression may break PDF/A compliance.
Documents with embedded forms — test compression effect on form fields before deploying.
Already-tiny PDFs (under 1MB) — compression overhead exceeds gains.
OCR layers — aggressive image compression can degrade OCR text recognition quality.

Common use cases

Quick use during a typical workday
Pre-decision sanity-check on inputs and outputs
Educational use — demonstrating the underlying concept
Onboarding a colleague who needs the same calculation/conversion

Frequently asked questions

How much smaller will it be?: Depends on content. Image-heavy PDFs (photos, scanned documents): 50-85% reduction. Mixed text+image: 30-50% reduction. Text-only PDFs: 5-15% reduction (text is already efficient). Already-compressed PDFs (passed through compression once before): 10-20% additional reduction. Try medium quality first — it's usually the right balance for screen reading.
Will quality suffer?: At high-quality (300 DPI / 85 JPEG quality), virtually no visible degradation for screen reading and most printing. At medium (200 DPI / 75), screen quality is fine; small text in images may show slight artifacts. At low (150 DPI / 65), suitable for email-only sharing where the recipient just needs to read; not for print. Always preview the result on the target device (phone, computer, printer) before deploying.
Why did my text-only PDF barely shrink?: Text in PDFs is stored as vector data (font references + positioning), which is already extremely efficient — compression has nothing to optimize. The bulk of file size in image-heavy PDFs is image data. If your PDF is 10MB and almost all text, it likely has duplicate fonts embedded or accumulated revision history. Try a tool like Adobe Acrobat's “Reduce File Size” that strips redundant fonts and edit history.
What's PDF/A?: An ISO standard for long-term archival PDFs (PDF/A-1, A-2, A-3). PDF/A files embed all fonts, prohibit certain features (encryption, JavaScript), and standardize compression to ensure files are renderable decades from now. Aggressive compression can break PDF/A compliance. If your document needs to comply with PDF/A (legal records, government archives), use a tool that specifically supports compressed PDF/A output.
Can I split a large PDF instead?: Yes, often a better solution. If your PDF is 50MB because it's 200 pages, splitting into 4 smaller PDFs (50 pages each, ~12MB each) lets you email them separately. Use the PDF-split tool. For sharing the original whole document, use a cloud drive (Drive, Dropbox, OneDrive) link instead of attaching — virtually unlimited size, recipients can preview without downloading.
What about online PDF compression services?: Many exist (Smallpdf, ILovePDF, Adobe Acrobat online). Trade-off: convenient but uploads your file to their servers. For confidential documents (contracts, medical records, financial statements), browser-based local compression is essential. Their free tiers also limit file size and number of compressions per day. For pure convenience on non-sensitive docs, online tools are fine; for anything sensitive, use local-only tools.

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