Compress PDF
Shrink PDF file size without losing quality.
or drag and drop · max 50 MB
PDF files have a way of becoming inconveniently large at exactly the wrong moments — when you're trying to email a contract, upload a portfolio to a job application portal, attach a brochure to a CRM, or push a long report into a chat tool that caps attachments at 10 MB. Most of the time the size comes from embedded images (scanned pages, high-resolution photographs, screenshots) that are stored at far higher fidelity than the final use actually needs. iSavePDF's Compress PDF tool re-encodes those images at lower-but-still-readable quality, strips redundant metadata, and rewrites the file structure to be smaller — all in your browser, with no upload to any server. Most PDFs come out 40-70% smaller than the original; image-heavy scans often shrink by 80% or more. Text remains crisp because text in a PDF is a vector instruction set, not pixels — compression only touches the image components. Critically, your file never leaves your device. Contracts with signatures, financial statements, medical records, internal company documents, and tax returns all stay on your machine throughout the whole process. There's no signup, no daily limit, and no watermark added to the output.
Step by step
How to compress pdf on iSavePDF
Open Compress PDF on iSavePDF
Visit isavepdf.com/compress-pdf in any modern browser — Chrome, Edge, Safari, Firefox, or Brave on desktop or mobile. No app to download, no account to create. The page works offline once cached, so you can compress files on a train or plane without giving up the tool.
Drop your PDF into the upload zone
Drag a PDF from your file manager onto the upload zone, or click to pick one. The tool accepts a single PDF at a time, up to about 50 MB. Larger files (50-200 MB) sometimes work depending on your device's available memory, but you'll see better performance compressing smaller batches.
Pick a compression preset
Choose between high, medium, or low quality. High keeps images at near-original fidelity and produces the smallest reduction (often 10-20%) — good for print-grade documents. Medium is the sweet spot for most uses (40-70% reduction, images still very readable). Low maximises compression at the cost of visible image quality — useful for proofreading copies, archival storage, or quick email previews.
Click Compress and wait a few seconds
Hit the Compress button. Your browser does all the work locally — extracting images from the PDF, re-encoding them at the chosen quality, and rebuilding the file. A progress indicator shows where you are. Most PDFs compress in well under ten seconds; very large or image-heavy files may take longer on slower devices.
Download the smaller PDF
When compression completes, your browser shows the new file size next to the original, plus the percentage saved. Click Download to save the smaller PDF to your device. The original PDF is untouched — nothing was modified in place, and no copy of either version was ever uploaded.
How it works
How Compress PDF works
Upload your PDF
Drop your file into the upload zone or pick it from your device.
Choose a quality level
Pick high, medium, or low compression depending on whether you need maximum quality or smallest file size.
Download the smaller PDF
We compress in your browser and hand you the result — no copy is kept anywhere.
When to use it
Common use cases
Email attachments under the size cap
Gmail caps attachments at 25 MB. Outlook ranges from 20-150 MB depending on your plan. Most corporate email gateways strip anything over 10 MB silently. Compressing a 30 MB PDF down to 8 MB lets you send it as a normal attachment instead of falling back to a shared drive link the recipient will half the time not bother to click. Particularly useful for contracts with scanned signatures, expense receipts photographed on a phone, and design proofs where each page is essentially a large image.
Job applications, portals, and submission forms
Application portals — for jobs, university admissions, visa applications, grants, and tenders — almost always enforce strict file-size limits, often 2-5 MB per upload. A CV with a single photo and a few embedded graphics can easily exceed that. Compressing first lets you submit on the first try instead of fighting the form. The privacy angle matters here too — your CV contains your full name, address, employment history, and education details. Most online compressors upload it to a server you don't control before doing anything with it. iSavePDF keeps it on your device.
Storing scanned archives without burning disk space
If you scan paper documents (tax records, receipts, signed paperwork, medical forms, lease agreements), the resulting PDFs are essentially photographs of each page and balloon in size fast — 5-15 MB per multi-page document is normal. Compressing each one before filing reduces archive size by 60-80% with no meaningful loss in legibility for everyday reference. A year of scanned paperwork that would have taken 5 GB takes 1-2 GB compressed. Backups become faster and cloud storage subscriptions cheaper.
Web hosting and CMS uploads
If you publish PDFs on a website — manuals, whitepapers, brochures, course materials, research papers — compressing them before upload makes them load faster for visitors and reduces your hosting bandwidth bill. A 12 MB whitepaper that takes 8 seconds to start displaying on a slow connection becomes a 3 MB file that opens almost instantly. Search engines also factor download speed into how they rank pages that link to PDFs, so smaller files indirectly help SEO.
Why iSavePDF
The privacy-first way to compress pdf
Most free online PDF compressors work the same way: you upload your file, their server compresses it, and they send the smaller version back. That round trip is fine for PDFs you'd be comfortable mailing to a stranger — but a huge percentage of PDFs people compress are exactly the kind that shouldn't be sent to strangers. Contracts with signatures and counterparty information. Financial statements with account numbers visible. Tax returns with social security or national-ID numbers. Medical records with diagnoses and dates of birth. CVs with personal contact details and employment history. The server-side model means your file is sitting on someone else's storage for at least the seconds it takes to process, often longer if their cleanup job runs hourly or daily, and is potentially logged in their pipeline.
iSavePDF compresses entirely in your own browser using pdf-lib for PDF manipulation and the browser's native image decoders for re-encoding. Your file is loaded into your tab's memory, the compression runs there, and the result is handed to your browser's download mechanism — there's no network round trip for the file content at any point. You can verify this yourself: open DevTools, switch to Network, and run a compression. You'll see zero outbound requests carrying your PDF. The tool is free with no enforced limits beyond what your device can handle, no signup, no watermark, no upsell. We fund the site with banner ads on the page — not by analysing or monetising your documents.
Tips & limits
Tips for the best results
Medium is right for most people
Unless you have a specific reason to pick another preset, medium quality is the right default. It typically produces 40-70% reduction with images that remain visibly clean and text that stays sharp. Low compression is more aggressive but introduces visible artefacts in detailed images — pick it only when file size matters more than quality. High compression preserves quality almost perfectly but only gets you a small file-size reduction.
Compression won't shrink already-optimised PDFs
If your PDF was generated by Microsoft Word's PDF export, LaTeX, or any modern PDF generator, it's already reasonably optimised — there's little image data left to compress. You may see only a few percent reduction. The biggest wins come from scanned documents and PDFs containing high-resolution photographs. If your PDF is already small but still won't fit a size limit, consider splitting it into pieces using the Split PDF tool, then compressing each piece separately.
Run it after merging, not before
If you're combining several PDFs into one, do the merge first and then compress the merged file. Merging doesn't recompress (it preserves originals losslessly), but compressing after merge lets the tool optimise images across all pages in one pass and strips redundant metadata that would otherwise be duplicated for each source file.
Text-only PDFs barely shrink
PDFs that contain only text (no images, no scanned pages) are already very efficient — text in PDFs is stored as vector instructions and embedded font subsets, not pixels. Compressing a 200-page text-only PDF might save 5-10% at best. If you need a smaller version of a text-only PDF, consider stripping pages you don't need with Delete PDF Pages or splitting into sections with Split PDF.
FAQ
Frequently asked questions
- Yes — completely free, no signup, no limits, no watermark, no upsell. iSavePDF runs banner ads on the page, which is how we keep the tools open and accessible. There's no paid tier or premium features for this or any other tool on the site.