How to reduce a PDF's file size for email without blurring the text

Open Compress PDF, drop in the file, and it is compressed straight away at Balanced. Compare page one before and after, try Small if you need it smaller, then press Download PDF. Text and fonts are never turned into pictures, so they stay sharp at every level.

Steps

1. Open Compress PDF and drop the PDF onto the box, or click to choose it. Compression starts on your device as soon as it is chosen.
2. Under Compression, pick Small, Balanced or High quality. The result updates when you switch, so you can try each and compare sizes.
3. Drag the divider across the preview to compare page one of the Original and the Compressed copy.
4. Read the sizes under the preview, and how many of the file's images were made smaller.
5. Press Download PDF. The copy is named after your file with -compressed added; the original is not changed.

Which level to pick

For a sense of scale: 1200 px across a full A4 page is about 100 dpi, fine on a screen; 1800 px is about 150 dpi; 2600 px is about 220 dpi.

What actually gets smaller

Most heavy PDFs are heavy because of photos: scans, product shots, pictures pasted in straight from a camera. The tool works on two things.

• Photos. Photos larger than the level allows are scaled down and saved again as JPEG. A photo is only swapped in when the new copy is clearly smaller. Photos in print colour spaces such as CMYK are left exactly as they are.
• The file's structure. Internal objects are packed into compressed streams, data that is already compressed is compressed again at the strongest setting, and resources that no page uses are dropped. This part loses nothing.

Links, bookmarks and form fields come through unchanged.

Why some PDFs barely shrink

A PDF that is mostly text is usually small already, and one saved by a careful program has little left to give. For those, the saving may be a few percent. If nothing makes the file smaller, the tool says so ("Already compact") and offers no new download, because a copy the same size or bigger would not help.

Scans and photo-heavy PDFs shrink the most, because that is where large photos sit.

When compressing is not enough

• Remove pages nobody needs. Cover sheets, blank backs and appendices add weight. Extract PDF pages keeps only the pages you choose, and often saves more than any compression level.
• Send it in parts. Split PDF shows each part's size before you download.
• Start from smaller photos. If you are building the PDF from pictures, compress the pictures first with Compress image, then make the PDF.

For a form with a strict cap such as 200 KB or 1 MB, see how to get a PDF under 200 KB or 1 MB.

Questions

Will compressing make the text blurry?

No. Text, fonts and drawings are kept as they are. Only photos are scaled and saved again, and the preview lets you check page one first.

Can I compress a password-protected PDF?

Yes, if you know its password. Enter it when asked; it is checked on your device. The compressed copy has no password, so add one again with Protect PDF if it needs one.

Is there a size limit?

No fixed limit. The file is processed on your device, so the ceiling is its memory. Large files take longer on a phone.

Is the PDF sent anywhere to be compressed?

No. It is compressed inside your browser and never stored on a server.