Compress a PDF on Android without installing an app

The steps in Chrome

1. Open the compressor in Chrome: this page, or getpdfs.app/compress-pdf. The first time you pick a file, it fetches its engine (4.6 MB, once) and keeps it on the phone.
2. Tap Choose files. Android opens its file picker. Look in Downloads, Recent, or the folder your scanner app or WhatsApp saves to, and tap the PDF. Several files at once are fine.
3. Choose how small. Email (pictures at 110 dpi) is selected by default and suits anything read on a screen. If a portal or form names a number, type it in the Size target field and pick KB or MB, or open the ready-made page: 100 KB, 200 KB, 500 KB, 1 MB.
4. Tap Compress and read the result: size before and after, and on a target, the resolution it took. If the target cannot be reached, it says so, with the size its strongest setting reached.
5. Tap Download PDF. Chrome saves the copy, named after your file with -compressed on the end, to the Download folder. Your original stays untouched.
6. Share it. Open Chrome’s menu, then Downloads, or your Files app, and share the file from there.

Why the “free” compressor apps are not the shortcut they look like

The store has dozens of PDF compressor apps, and the trade is often the same: ads, a sign-up or a weekly limit, and for many of them the compression happens on the developer’s server, not on the phone. That is a lot to accept for a job a web page can do on the device.

If you do install one, read what it declares first. Every app on Google Play has a Data safety section on its store page; tap See details to see what data the developer says the app collects and shares, and why (Google Play Help, checked on 11 October 2026). It is the developer’s own declaration, not an audit, but an app that lists your files as shared tells you enough.

The browser route needs no such trust: you can watch it work offline, as the last section shows.

Phone scans and photos: why they are big

Most oversized PDFs on a phone are made of pictures: a scanner app’s pages, or photos turned into a PDF. A 12-megapixel camera photo is about 3 MB, so a 5-photo PDF is near 15 MB before anyone has typed a word. Our test file of 5 such photos (14.7 MB) comes out at 395 KB on the Email preset, 110 KB on a 200 KB target and 58 KB on a 100 KB target.

Scans of paper behave a little differently: each scanned A4 page costs about 180 KB at 110 dpi and about 60 KB at 72 dpi, so a 100 KB cap fits about 5 scanned pages and 200 KB about 10. If a portal wants 100 KB and you have 12 pages, the honest answer is fewer pages or several uploads; the portal size limits guide covers which portals allow that.

Sending it from the phone

• WhatsApp: in the chat, tap the attachment button, choose Document, and pick the compressed file from Downloads. Sending it as a document keeps it as the PDF it is.
• Email: attach from Downloads in Gmail or any mail app. Providers cap attachments at around 20 to 25 MB; the Email preset gets almost any phone PDF well under that.
• Portal uploads: in Chrome, the portal’s upload button opens the same file picker. Pick the copy, not the original; they sit side by side in Downloads, and the -compressed ending tells them apart.

The honest part: memory, and what this cannot do

A phone has less memory than a laptop. The tool reads the memory Chrome reports and keeps its work inside it. A typical phone PDF of tens of MB is fine. A very large file on a phone with little memory (a 300 MB scan on a 3 GB phone, say) may be too much. When the tool can see that a step will not fit, it stops with a sentence that says how much the step needs and how much the browser has to work with; in the worst case Chrome reloads the tab instead. Either way, the fix is the same: split the file and compress the parts, or do that one file on a computer.

Compression cannot shrink text. A PDF that is mostly typed text is already small. The tool says so and gives you the original back rather than a file that is no smaller.

It is lossy for pictures. Photos and scans are re-encoded and some detail goes for good. Keep the original; send the copy. Check the smallest print at 200 percent before you send.

Check that nothing is uploaded, with aeroplane mode

Compress one file with the network on, so the engine is fetched and kept on the phone. Then turn on aeroplane mode, reload the page and compress another file. It still works: the PDF is processed in Chrome on your phone, and there is nowhere for it to go. The same test works on an iPhone; see compress a PDF on iPhone. For the wider picture of keeping documents private, read PDF privacy and protection.