PDF圧縮ツール

What this tool does

Rewrite a PDF with Low, Balanced, or Strong compression and compare the sizes. Use Balanced on a text report when the words should stay selectable. Strong turns each page into a JPEG, so a smaller file is not guaranteed and the text is no longer selectable.

How to use

1. Choose a PDF from your device. The file stays in this browser tab.
2. Pick Low compression (rewrite, keep text), Balanced (copy pages into a new file), or Strong (rasterize pages to JPEG).
3. Press Compress and check original size, output size and the change percentage.
4. Download the result if it is useful. Reset to try another file or preset.

Examples

• A text-heavy report

  Start with Balanced. Many already-compressed PDFs barely shrink. Strong would replace selectable text with images, which is usually the wrong trade for a report.

• A scan made of page photos

  Strong compression can reduce size by re-encoding pages as JPEG. Text will not stay selectable. Low and Balanced often change little on files that are already JPEG pages.

How it works

Low and Balanced rewrite PDF structure without turning pages into pictures, so vectors and text stay. Strong renders each page to a JPEG and rebuilds the document, which can shrink photo-heavy files and will destroy selectable text. Tools Star Hub does not claim a guaranteed reduction. Some files stay similar in size or grow slightly.

Limitations

A smaller file is not guaranteed. Balanced compression can leave an already-compressed PDF about the same size. Strong compression turns each page into a JPEG, so the text is no longer selectable. A very large PDF can be slow or fail if the device is low on memory.

See the disclaimer for what these tools do not cover.

FAQ

Is the PDF Compressor free?

Yes. You can compress a PDF in this browser without paying or creating an account.

How do I compress a PDF?

Open the PDF Compressor, choose the file, pick a preset, then compress and download. Processing stays in your browser.

Will every PDF get smaller?

No. If the file is already compressed, a rewrite can stay about the same size. Strong rasterization can even grow a simple text PDF.

Is this lossless?

Low and Balanced keep page content as it is and only rewrite structure. That is not a promise of smaller files. Strong is lossy because pages become JPEG images.

Does it work on mobile?

Yes. You can open this page on a phone or tablet. File pickers and downloads use the browser on your device. Large files may be slower on a small phone than on a desktop.