Compress PDF
Make a PDF smaller so it is easy to email or upload. Choose how much to compress and see the size before and after. The work happens in your browser, so the document is never uploaded, and you only get a file if it is genuinely smaller.
Drop a PDF file here
PDF only, up to 200 MB. One file at a time.
Your files stay in this browser tab. Nothing is uploaded, saved or logged.
How Compress PDF works
Most of the weight of a PDF is its pictures: a scanned page or a photo is stored as a JPEG that is often far larger than needed. At the Balanced and Strong levels, each large JPEG picture is decoded, scaled down so its longest side is at most 2,200 or 1,500 pixels, and encoded again at a lower quality. Text and vector drawings are not pictures, so they stay perfectly sharp.
After the pictures, the whole file is rewritten with a PDF optimiser (qpdf, compiled to run in your browser): objects are grouped into compact streams and every compressed stream is recompressed at the highest setting. This step changes nothing you can see, and it is the only step of the Lossless level. It helps most on files made by programs that store data wastefully.
The result is checked before it is offered: the file must be at least 1% smaller than the original. If it is not, no file is produced and the tool says so, rather than handing you something larger. Your original is never modified.
How to use it
- Select a PDF file, or drop it on the area at the top of the tool.
- Choose a level. Balanced suits most documents; choose Strong for the smallest file, or Lossless if nothing may change.
- Choose Compress PDF and wait while the pictures are processed. You can cancel at any time.
- Check the sizes before and after, then download the file. If you want a smaller one, choose Try another level.
Example
| Level | Effect on pictures |
|---|---|
| Lossless | Pictures untouched. Only the way the file is stored changes. |
| Balanced | A 4032 × 3024 px photo becomes 2200 × 1650 px at 75% quality. |
| Strong | A 4032 × 3024 px photo becomes 1500 × 1125 px at 55% quality. |
Limits and good to know
- The PDF can be up to 200 MB. The document is held in your device’s memory while it works, and recompressing large pictures takes time: a scan of many pages can need a minute or more.
- Only pictures stored as ordinary JPEG are recompressed. Pictures in other encodings (PNG-style, JPEG 2000), CMYK pictures, and pictures with masks are left as they are, so a PDF made mostly of those shrinks little.
- Password-protected PDFs cannot be processed. Remove the protection first, which requires the password. Bookmarks, form fields and links are kept, because the document structure is not rebuilt.
Frequently asked questions
Is my PDF uploaded to a server?
No. The document is opened and compressed by your own browser and nothing is sent anywhere. You can check it in your browser’s developer tools: the Network tab shows no upload while you compress. Closing the tab or pressing Start over releases the document from memory.
Will my text become blurry?
Not if the text is real text, which is the case for documents exported from a word processor or a website: text is never touched. A scanned document is different: each page is a picture of text, so shrinking the picture also softens the letters. For scans, start with Balanced and check the result before using Strong.
Why could my PDF not be made smaller?
Because there was little to gain. A PDF made of text and vector drawings is already compact, and one whose pictures are small or already heavily compressed has nothing left to shrink. Pictures stored in formats other than JPEG are also left alone. The tool then says so and produces no file.
Which level should I choose?
Balanced for most documents: it keeps pictures clear on screen and on a normal printout while cutting the size a lot. Strong when a size limit forces you, for example an upload form. Lossless when the pictures must not change at all, accepting a much smaller saving.
Does it change anything besides the pictures?
The rewrite step reorganises how the file is stored, not what it shows, and bookmarks, form fields and links are kept. The producer name in the document properties may change. Compare the result with the original before you replace it, as with any conversion.