Compress PDF Known limits

Shrink a PDF by recompressing embedded images and stripping waste.

Worth knowing before you startClient-side compression with permissively-licensed tools typically achieves 20–50% size reduction by downsampling embedded images and stripping redundant objects. This is honest and useful — but it is not the 70–90% reduction that server-side Ghostscript achieves by fully re-rendering the document. If you have a 50 MB CAD-generated PDF full of high-resolution vector art, this tool will help but will not transform it into a tiny file.

Choose PDF file or drop it anywhere on this page PDF Processed on your device — never uploaded

This tool does its work with JavaScript in your own browser — that is exactly why your files never get uploaded. Please enable JavaScript to use it.

How to compress pdf

Open a PDF and see the current file size.
Adjust image quality and DPI to taste — lower means smaller.
Compress and compare the before/after size before downloading.

About this tool

PDF files get large for two main reasons: high-resolution raster images embedded in the page stream, and accumulated redundancy from incremental edits. This tool addresses both by downsampling images that are denser than the target DPI and stripping the dead weight from the cross-reference table.

The honest limitation is that client-side tools cannot re-render a document from scratch the way Ghostscript can. If a page was designed at 600 DPI print resolution and you want it at 72 DPI screen resolution, Ghostscript re-draws every element at the lower density. A browser-side tool resamples the raster images but cannot touch vector content. For most scanned documents and image-heavy PDFs, the 20–50% range is still worth having — especially when the alternative is uploading sensitive files to a remote server.

Questions

How much will it actually shrink my file?

It depends entirely on what is inside. A 10 MB PDF full of scanned-in photos can come down to 3–5 MB with quality at 65 and 150 DPI. A 10 MB PDF full of text and vector diagrams may shrink by only 5–10%, because text and vectors are already stored efficiently and this tool does not touch them.

Why not 70–90% compression like some services advertise?

Those numbers are real but come from Ghostscript running server-side, which re-renders every page at a fixed DPI. That is expensive software running on a server, which is why those services either charge or show ads. This tool runs entirely in your browser using only freely available WebAssembly libraries, which means no upload — a genuine privacy win — at the cost of less aggressive compression.

Will text quality suffer?

No. Text and vector content are not touched; only raster images embedded in the PDF are resampled. If your PDF is mostly text, you will see modest gains with no perceptible quality change.

Compress PDF Known limits

How to compress pdf

About this tool

Questions

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