Small file. Big relief.

An attachment is supposed to make a conversation easier. When a PDF will not send, the useful question is not “How small can I make it?” It is “How small does this copy need to be?” Keep your original, then make a version for sharing.

Start with the actual limit

Check the upload limit on the form or service you are using. Leave some room below it: email attachments can grow when encoded for transmission, and a message may include several files. A 20 MB limit does not necessarily mean a 20 MB PDF will fit comfortably.

Make a lighter copy

1. Open Compress PDF and select your document.
2. Start near the middle of the compression slider. Higher settings favor a smaller file; lower settings favor detail.
3. Run the tool and download the result.
4. Compare the new file size with your target before trying a stronger setting.

Compression is most useful when images account for much of the file. A PDF containing mostly text may already be compact. It is normal for some documents to shrink very little.

Check the parts that matter

Open the new copy at normal reading size. Inspect small print, signatures, charts, and any scanned handwriting. Then zoom into one detailed image. If characters blur together, try a gentler setting from your original rather than compressing the compressed version again.

When compression is not enough

Remove irrelevant cover sheets with Remove Pages, or send only the needed section using Split PDF. If every page and image matters, a permitted file-sharing link may be more appropriate than a heavily degraded attachment.

A useful download is readable and small enough for its destination. The smallest possible file is not always the best one.