Compress PDF Online — Free, Fast, No Sign-Up
Compress any PDF file online for free. Choose your quality level and shrink your file by up to 70% in seconds. No sign-up, no software required.
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How to Compress a PDF — 3 simple steps
PdfDocShift's PDF compressor uses Ghostscript under the hood — the same engine trusted by print professionals worldwide. Upload your PDF, choose a compression level, and download a smaller file in seconds. No watermarks, no quality surprises, no sign-up.
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No sign-up required. Files are encrypted in transit and auto-deleted after 2 hours.
Why Is My PDF So Large?
PDF files balloon for a few predictable reasons. The most common culprit is unoptimised images — when you export from Word, InDesign, or scan a physical page, embedded images are saved at full resolution (300 DPI or higher) with no further compression applied. A single full-page scan can weigh 3–5 MB on its own. The second factor is embedded fonts: PDFs bundle a copy of every typeface used, which can add hundreds of kilobytes per font variant. Finally, PDFs sometimes carry hidden redundant data — old edits, embedded colour profiles, duplicate objects — that accumulates over multiple save cycles. Ghostscript, the engine behind this tool, strips all of that out and re-encodes images at the optimal resolution for digital display.
Low, Medium, or High — Which Compression Level Should You Choose?
Low quality targets the absolute smallest file size by aggressively downsampling images to 72 DPI and discarding metadata. Use it when file size is the only priority — bulk archiving, internal references, or uploading to portals with strict size limits. Quality loss will be visible on image-heavy documents. Medium quality (the default) is the right choice for most people. Images are resampled to 150 DPI — sharp enough for on-screen reading and standard printing, while cutting file size by 40–70%. This is ideal for emailing reports, uploading to websites, or sharing via messaging apps. High quality applies minimal compression, preserving images close to their original resolution. The reduction is smaller (typically 10–30%), but the output looks nearly identical to the source. Best for documents that will be printed professionally or need to pass visual inspection.
What File Size Should I Target?
Most email clients cap attachments at 10–25 MB, but staying under 5 MB ensures smooth delivery across all providers including Gmail and Outlook. Many government, HR, and finance portals enforce a 5 MB or even 2 MB upload ceiling — always check the portal's stated limit before compressing. For PDFs published on a website or linked in a blog post, staying under 1 MB significantly improves load time, especially on mobile connections. General rule: Medium compression covers most email and web use cases; switch to Low only when you need to hit a hard size ceiling and visual fidelity is secondary.
Compress PDF questions
Everything you need to know about compressing PDF files online.
Compression results vary depending on PDF content. PDFs with many images can be reduced by 50–70%. PDFs with mostly text may see 10–30% reduction. Choose Low quality for the smallest file, Medium for a balanced result, or High to preserve maximum quality.
PDF compression primarily works by downsampling embedded images and removing redundant data. Text remains crisp and fully searchable at all compression levels. For best visual quality, choose the High setting — for email attachments, Medium is usually ideal.
The maximum upload size is 200 MB. If your file is larger, try splitting it into smaller parts first, compressing each, then merging them back together using our Merge PDF tool.
Yes. All files are transferred over 256-bit SSL and stored in encrypted cloud storage tied to your anonymous session. No one else can access your files, and they are permanently deleted after 2 hours. We never read or share your documents.