Find the PDF on your phone
A PDF you received as an attachment may only exist inside the mail or messaging app that delivered it. Before you can compress it, save it somewhere your browser can reach: on iPhone and iPad, use the share action to save it to the Files app; on Android, download it so it lands in the Downloads folder.
Note the file’s current size while you are there. The Files app shows it in the item’s info, and Android file managers show it in the details view. Knowing that the file is 14 MB and the limit is 5 MB tells you how much reduction you need, which guides the level you pick in a moment.
Check the actual limit, too. An upload portal or a recipient’s mail system may allow less than you assume, and your target is the limit that applies at the destination. Aiming comfortably below it avoids a second round of compression when the file is only just too large.
Compress it in your phone’s browser
Open Compress PDF in Safari, Chrome or whichever browser you use, tap to choose a file, and pick the PDF from Files or Downloads. Select a compression level, run it, and download the smaller copy. The original is left exactly as it was.
The compression runs on your phone, inside the browser tab, and the document is never uploaded to a server. That matters for the kinds of PDFs people send from their phones in a hurry — bank statements, ID documents, medical letters and signed contracts. Being quick should not mean handing a private file to an unknown service.
Keep the tab in the foreground while it works. Phones pause background tabs to save battery, and switching to another app mid-compression can stall the job. A long scanned document takes noticeably longer on a phone than on a computer, and that is normal.
Choose a level for the document
There are three levels: Light, Recommended and Strong. Recommended suits most documents and is where to start. The choice is a trade-off between file size and how crisp the pages look, and the right answer depends on what is in the PDF and how small it needs to be.
| Level | Use it when | Watch for |
|---|---|---|
| Light | The file is only slightly over the limit, or has small print | Modest savings |
| Recommended | Most scans and mixed documents | Check small text and signatures |
| Strong | A large scan that must fit a strict limit | Fine detail and faint text may soften |
Start one step lighter than you think you need. If the result is still over the limit, step up a level and compress the original again — not the already-compressed copy. Compressing a compressed file stacks the losses and degrades the pages faster than a single, stronger pass.
Know what compression changes
This compressor rebuilds each page as an image. That is why it works so well on scans and photo-heavy PDFs, and it is also its main trade-off: text in the compressed copy is still visible, but it is no longer selectable or searchable. For a scanned document that never had selectable text, you lose nothing.
For a PDF that was created digitally — an exported report or an e-statement — the trade-off is real, and the saving is usually smaller anyway, because text is already stored efficiently. If the recipient needs to copy text from it, consider whether compression is the right fix at all, or run OCR PDF on the compressed copy to add a searchable text layer back.
Links and fillable form fields do not survive being turned into images either. If the PDF is an interactive form you still need to complete, fill and save it first, then compress the finished copy — or skip compression and reduce the size another way, as below.
When the file is still too big
If Strong is still over the limit, the PDF probably contains more than the recipient needs. Remove pages with Remove PDF Pages — blank backs of scanned sheets, duplicate pages, appendices nobody asked for — and compress what remains. Fewer pages beat harsher compression every time.
Alternatively, split the document and send it in parts, if the destination accepts several files. A 40-page bundle split into two 20-page PDFs halves the size of each without touching the quality, and that is often better than squeezing one file until the small print disappears.
Very large PDFs can also exceed what a phone browser can handle in memory. If compression stalls or the tab reloads, close other tabs and try again, or do the job on a computer. The Windows and Mac guides cover the desktop route.
Check the result, then share it
Open the compressed PDF on your phone and zoom in on the smallest text — a footnote, a reference number or a signature. Your phone screen is small enough to hide blur at normal zoom, but the recipient will probably read it on a larger screen. If anything important has gone soft, compress the original again at a lighter level.
Confirm the new size against the limit, and check the page count matches the original. Then share the compressed copy from the Files app or your Downloads folder using the normal share action, so you attach the new file rather than the original sitting in your mail app.
Keep the original until the recipient confirms they have what they need. If they ask for a clearer copy or the full version, you will want the uncompressed file — and on a phone, where it is easy to lose track of which copy is which, a clear filename such as “statement-compressed” helps.
Open Compress PDFThree levels, runs in your phone’s browser — nothing uploaded.
Open Compress PDF →Frequently asked questions
Do I need an app to compress a PDF on my phone?
No. A browser-based compressor works in Safari or Chrome on your phone, and the file is processed on the device rather than uploaded.
Why can't I select the text after compressing?
PDFNest’s compressor rebuilds each page as an image, which is how it achieves large savings on scans. The text is still visible but no longer selectable; run OCR afterwards if you need it searchable.
Why did my PDF hardly get smaller?
Text-based PDFs are already compact, so there is little to remove. Large savings come from scans and photo-heavy documents. For a text PDF, removing unneeded pages is usually more effective.