Email attachment limits vary, but the practical problem is universal: a document can be small enough to send and still look poor on the recipient’s screen.
Good PDF compression balances size, readability, and document behaviour. The right result is not necessarily the smallest possible file.
Check the document before compressing
First identify what makes the PDF large. Common causes include:
- high-resolution photographs or scans;
- many full-page images;
- duplicated pages;
- embedded fonts;
- complex graphics; and
- a scan resolution far beyond what the recipient needs.
Remove unnecessary pages before compressing. If you control the source document, exporting it again with sensible image settings can produce a better result than compressing the PDF later.
Compress the PDF in your browser
- Open Compress PDF.
- Select the PDF from your device.
- Choose the available quality or resolution option appropriate to the document.
- Run the compression and download the result.
- Compare the original and compressed files side by side.
PDF Pouch performs this workflow locally in the browser tab. The selected document contents are not uploaded to a PDF Pouch application server.
Use a quality checklist
Read text at normal zoom
Open the result at 100% and check small text, footnotes, table labels, and light-coloured type. A document that looks acceptable as a thumbnail may be difficult to read at ordinary size.
Inspect detailed images
Look closely at diagrams, QR codes, barcodes, screenshots, signatures, and fine lines. Compression artefacts around high-contrast edges can interfere with scanning or interpretation.
Test search and selection
Some compression methods rasterise pages. The page may still look correct while text selection, search, copy and paste, accessibility, and screen-reader behaviour are lost. PDF Pouch clearly notes when an operation uses that trade-off.
Recheck links and document features
Forms, annotations, layers, attachments, and digital signatures may not survive every transformation. If those features matter, test them in the downloaded result. A transformed PDF should not be assumed to preserve an existing cryptographic signature.
What file size should you target?
Use the destination’s published attachment limit and leave some margin. Email systems can add transfer overhead, and the sender’s limit may differ from the recipient’s.
For a document that will be downloaded from a website or opened after scanning a QR code, focus on mobile loading time as well as the raw limit. Test the actual link over a mobile connection and confirm that the first useful page appears quickly.
When not to compress
Avoid unnecessary compression when:
- the document is already comfortably within the limit;
- fine print or technical diagrams must remain pristine;
- searchable text or accessibility is essential;
- the file contains a digital signature that must remain valid; or
- an approved records process requires the original format.
In those cases, use an authorised file-transfer or document-hosting system rather than degrading the document to fit an email.
Keep both versions
Retain the original and label the smaller copy clearly. Reopen the exact attachment before sending it. If the recipient will print the file, test a representative page on paper as well as on screen.
Compression is successful when the recipient gets a smaller file without losing the information or functionality they need.