RSRobince Studio

Compress PDF

Make a PDF smaller for email or upload limits. Pick a method, see the before and after size, and download the result. Honest warning: the strongest mode turns text into pictures.

Runs in your browser. Your files are never uploaded.

Loading Compress PDF…

How to use Compress PDF

  1. Choose a PDF file.
  2. Pick Rebuild as images for the biggest savings, or Optimise structure only if text must stay selectable.
  3. For image mode, set the resolution and JPEG quality. Lower numbers make smaller files.
  4. Press Compress PDF, compare the sizes, and download only if the result is smaller and looks acceptable.

What really makes a PDF large

Most large PDFs are large because of images: scans, photographs and high-resolution graphics. Text itself is very small. A 50-page scanned document can easily be tens of megabytes because every page is a full-size photo, while a 50-page text report might be a few hundred kilobytes.

Real compression therefore means making the images smaller, either by lowering their resolution or by saving them with stronger JPEG compression. That is exactly what the rebuild mode does, applied to whole pages.

Choosing a mode

Use Rebuild as images for scanned documents and photo-heavy files where the text is already a picture anyway. A resolution around 100 to 130 dpi and quality of 60 to 70 percent is a sensible starting point for reading on screen; raise both if small print looks fuzzy.

Use Optimise structure only for text-based documents such as reports and contracts, where searchable, selectable text matters. Expect a modest saving at best.

  • Scanned or photo PDF: image mode, 100 to 150 dpi.
  • Text report that must stay searchable: structure mode.
  • Already small file: leave it alone.
  • Always keep the original and compare the result before sending.

Limits and privacy

This tool is not a full professional compressor. It cannot downsample images inside a PDF while keeping the text live, subset fonts, or remove duplicate resources. Image mode also drops links, form fields, bookmarks and signatures, so do not use it on signed or fillable documents.

All work is done by your browser, using pdf.js to draw pages and pdf-lib to assemble the new file. Nothing is uploaded. Very large documents use a lot of memory and may take a while on phones.

Why use this compress pdf tool

  • Two clearly explained methods. One re-renders pages as JPEG pictures; the other only re-saves the file with a tighter internal structure.
  • Adjustable quality. Control the dpi and JPEG quality to trade clarity for size.
  • Before and after sizes. See exactly how much was saved, and a warning if the result is not smaller.
  • No upload. Compression runs in your browser, so private documents stay on your device.

Frequently asked questions

Why does image mode make my text non-selectable?

In that mode each page is drawn to a picture and the pictures are placed into a new PDF. Anything that was text, including searchable words, links, form fields and bookmarks, becomes part of the picture. This is how the big size reduction is achieved, and it is why the tool warns you. If you need searchable text, use the structure-only mode instead.

Why did optimise structure only barely change the size?

This browser tool cannot recompress the images or fonts inside a PDF. Structure mode only re-saves the file using object streams, which packs the internal bookkeeping more tightly. Files that are mostly large images or embedded fonts usually shrink only a little, and some do not shrink at all.

Can the compressed file end up larger?

Yes. A text-only PDF is already tiny, and turning it into pictures at high dpi can make it bigger. The tool shows the sizes and warns you when there is no saving, so you can simply keep the original.

More free tools

PDF Merge

Combine multiple PDF files into one document in seconds. Free, no sign-up, no watermark, and your files never leave your device.

Open tool

PDF Editor

Edit PDFs in your browser: add text and images, white-out content, rotate, reorder or delete pages. Free, private, no upload.

Open tool

JPG to PDF Converter

Convert JPG, PNG and WebP images into a single PDF. Reorder pages, choose A4, Letter or fit-to-image size. Free and private.

Open tool