Last updated: August 1, 2026

Compress PDF Online – Reduce File Size for Free

Shrink PDFs for email, job portals, and uploads while keeping text sharp. Free in-browser tool with Low / Medium / High levels — no signup.

Upload PDFUpload

CompressCompress

Download PDFDownload

Upload PDF to Compress

Drag & drop your file here, or click to browse. We process files locally for maximum privacy.

Compress PDF Online – Reduce File Size Securely

Need to shrink a large PDF file for email or upload limits? Our Compress PDF tool helps you reduce the file size of your documents while maintaining great quality.

Choose from different compression levels to get the perfect balance between size and clarity. Best of all, since everything happens locally in your browser, your sensitive documents never leave your device.

How to Compress PDF Files in 3 Steps

Optimize your PDF documents quickly and easily.

Upload PDF

Drag & drop your PDF file or click to select from your device.

Choose Level

Select "Low", "Medium", or "High" compression based on your needs.

Download

Click "Compress PDF" and download your optimized file instantly.

Why Use Our PDF Compressor?

100% Secure

Files processed locally. No uploads.

Fast Compression

Optimize PDFs in seconds.

High Reduction

Significant size reduction results.

No Limits

Compress as many files as you want.

Custom Levels

Choose quality vs size balance.

Works Offline

No internet needed after loading.

The Complete Guide to PDF Compression

PDF compression reduces file size by optimizing the heaviest parts of a document: embedded images, fonts, and redundant data. A 50MB scanned report can often become a 5MB file that looks identical on screen. Understanding what gets compressed helps you pick the right level for email, uploads, archiving, or professional printing.

How PDF compression actually works

Four techniques do most of the work. Image downsampling reduces photo resolution from print quality (300 DPI) to screen quality (72–150 DPI). Image recompression converts bulky bitmaps to efficient encodings. Font subsetting keeps only the characters your document uses instead of entire font families. Object cleanup removes duplicate images, hidden layers, and metadata bloat left by editors. Our tool applies these automatically in your browser.

Choosing the right level

Use Low for anything headed to a print shop, court filing, or portfolio review — quality loss is minimal. Use Medium for homework submissions, job applications, and client drafts where files must look crisp but stay under 10MB portals. Use High for quick email attachments, chat sharing, and uploads with harsh size caps. When in doubt, start with Medium, inspect zoomed-in photos and small text, then re-compress at a different level if needed.

Common scenarios

Students shrink lecture scans before uploading to learning portals. Job seekers compress resume-plus-certificates bundles to fit 5MB application forms. Accountants reduce monthly statement packs for email. Real-estate agents compress inspection photo reports for listings. Anyone fighting a "file too large" error on a government, university, or visa portal will find High compression plus a follow-up Split PDF solves nearly every rejection.

Privacy and quality notes

Because compression runs locally in your browser, your documents never leave your device — a critical difference from upload-based compressors when handling passports, tax forms, and medical files. Compression never adds watermarks and never edits your text. Always keep the original file until you have verified the compressed copy, especially before deleting source scans.

Frequently Asked Questions

Common questions about our PDF compression tool

Is this Compress PDF tool free?

Yes, our Compress PDF tool is 100% free with no limits on file size or the number of documents. It is funded by clearly labeled display ads — never by charging you or selling your files. See our Advertising Disclosure in the Privacy Policy for details.

Is it safe to compress my PDF here?

Absolutely. Files are processed locally in your browser using client-side technology, so contracts, medical records, and financial statements never leave your device. We never store your documents and never use their content for advertising.

Will my PDF quality be affected?

You control the trade-off with Low, Medium, and High compression levels. Low keeps near-original quality for printing (good for portfolios and legal filings). Medium balances size and clarity for everyday sharing. High maximizes shrinkage for email attachments and uploads with strict limits. Text stays sharp in all modes; image-heavy pages shrink the most.

Can I compress PDFs on my phone?

Yes. The compressor works in mobile Chrome and Safari on iPhone, iPad, and Android. Upload from device storage or cloud drives, pick a compression level, and download the smaller file — ideal for shrinking photos of documents and lecture scans before submitting assignments.

How much smaller will my PDF get?

It depends on content. Scanned image-heavy PDFs often shrink 60–90%. Digitally exported reports with embedded images typically shrink 30–60%. Text-only PDFs are already compact and may only shrink 5–20%. If your file barely shrinks, its images were already optimized — try the High setting or compress embedded images at the source.

Why is my PDF so large in the first place?

Common culprits: high-resolution photos embedded at print resolution, duplicated fonts, uncompressed scans, and layered graphics from design tools. Exporting slides as PDF with full-quality images is another classic cause. Compression fixes this by downsampling images, subsetting fonts, and removing redundant objects.

Will compression remove passwords or signatures?

No. Compression preserves passwords, permissions, and digital signatures as-is. You must unlock a password-protected PDF with its password before compressing — the tool cannot bypass encryption. After compression, protections remain intact.

What should I do if the compressed file is still too big for email?

First try the High compression level. If still too large, split the PDF into parts with our Split PDF tool and send in batches, or share via a cloud link instead of attachment. Most email providers cap attachments at 20–25MB; university portals and job sites often cap at 5–10MB.

Can I compress multiple PDFs at once?

Compress files one at a time for the best quality control, since each document needs a different level. For bulk workflows — such as monthly invoice batches — compress each file, then join them with our Merge PDF tool into one optimized bundle.

When should I NOT compress a PDF?

Avoid heavy compression for print-shop submissions, architectural drawings, and medical imaging where every pixel matters — use Low compression or keep the original. Also keep an untouched backup of important originals before compressing, so you can always revert.