Compress PDF

How it works

1. 1

   Choose your PDF Start with Choose a file, or drag your PDF onto the upload area. The page shows its name, page count, current size and page previews.

2. 2

   Pick a level In the Compression level box, click one of the three options: Low, Medium or High. Medium is selected when the file opens.

3. 3

   Compress Press Compress and download. The button reads Compressing... while the server works on the file.

4. 4

   Check and download The result shows the Original and Compressed sizes and the Reduction in percent. The file name_compressed.pdf downloads as soon as it is smaller; Download again saves it once more if needed.

Low, Medium or High

At every level, images are saved again as JPEG at the level's quality, and images above a set resolution are also scaled down. Resolution is measured at the size each image has on the page, so a large photo placed in a small frame counts as high resolution.

• • Low: JPEG quality 82, and images above 160 dpi go down to 150 dpi. Pick it when pictures must stay close to the original.
• • Medium: quality 68, and images above 140 dpi go down to 120 dpi. A middle ground for files read on screen or sent by email.
• • High: quality 52, and images above 120 dpi go down to 96 dpi. It usually gives the smallest file, but photos can look softer when printed.
• • An image is replaced only if its new version is at least 12 percent smaller. Images with transparency and images of fewer than 8,100 pixels, the size of a 90 by 90 square, such as small logos and icons, are left as they are.

What else changes in the file

• • Fonts are cut down to the characters the document actually uses.
• • Attached and embedded files, scripts and stored page thumbnails are removed.
• • Form fields are reset to their default values, so keep the original of a form you have filled in.
• • The XMP metadata is removed, while the title and author stay. Links stay in place.

Files over 4 MB

The server accepts files up to 4 MB, and a task that takes longer than about 30 seconds fails. The page still sends a larger file first. When the server refuses it, or fails for any other reason, the page falls back to a lighter optimization in your browser, and the result screen says so. That optimization leaves images untouched and ignores the level you chose, so the gain is usually small.

To shrink a large file properly, cut it into parts of less than 4 MB with Split PDF, compress each part, then join them again with Merge PDF. This does not work for a single page heavier than 4 MB.