PDFs are one of the more common things people want to listen to instead of read: research papers, reports, scanned forms, long attachments someone emailed you. On Android, the built-in tools get partway there, but they were mostly built for a different job than continuous, hands-free listening.
Select to Speak: reads what's on screen, not the document
Select to Speak is Android's built-in accessibility feature for reading text aloud. Turn it on under Settings, Accessibility, Select to Speak, and you get a floating button that lets you tap or draw a box around text to have it read out.
The limitation, and it is a consistently reported one, is that Select to Speak works with what is currently visible on screen, not the document as a whole. Select a paragraph, it reads that paragraph. Scroll down, select again, it reads the next chunk. For a short PDF that is a couple of screens long, this is a manageable, if repetitive, way to get through it. For a ten-page report or a research paper, it turns into a lot of scrolling and re-selecting, and it does not accumulate into anything like continuous playback you could leave running in the background.
It is also, by design, an on-demand tool rather than a document reader: there is no library of things you have converted, no resume point, and no way to keep it running once you switch to another app or lock the screen.
Google's other read-aloud options, described generally
Beyond Select to Speak, Android and Google's own apps have some additional read-aloud capability, though it is worth describing generally rather than precisely, since it varies by app version, device, and which PDF viewer or ebook app you are using. Some PDF viewers on Android include a "read aloud" or accessibility mode tied into TalkBack, Android's full screen reader, which is built for navigating an interface by voice rather than casual audiobook-style listening. Google Play Books has text-to-speech support in some contexts for books in its own library, again generally oriented around accessibility rather than a queue-and-play experience.
None of these are consistently marketed or documented as a "listen to this PDF like a podcast" feature, and their availability and behavior can differ from one Android version or manufacturer skin to the next. If you have tried one and found it works well for your specific PDF and device, that is worth sticking with. If it has been inconsistent, that inconsistency is a commonly reported experience, not just you.
The ReadLoud flow: upload, then play with the screen off
Because the built-in options are tied to what is visible, the more reliable path for a full PDF is to convert it into audio first, then play that audio the normal way any audio plays, continuing with the screen locked.
The flow is short. Open readloud.app (it also installs as a home screen app on Android), upload the PDF, and it gets processed into a document in your library. From there, press play and the screen can go dark exactly like a music or podcast app, with no repeated selecting required. Nothing is generated until you press play, and generation runs a little ahead of where you are listening, so the first couple of seconds of a document take a moment while the rest keeps pace as you go.
PDFs are extracted the way a reader view extracts a web page: navigation, headers, footers, page numbers, and citation brackets are generally stripped out because they interrupt reading flow, and any text ReadLoud was unable to extract cleanly is shown dimmed in the document view rather than silently dropped. That matters more for PDFs than most formats, since PDF layout (columns, footnotes, running headers) is one of the least standardized things reading software has to deal with.
Word-by-word highlighting, measured from the actual generated audio rather than estimated, follows along as it plays, useful for research papers or reports where you want to glance back at exactly where the voice is or click a word to jump the audio there.
Listening across devices, and sharing what you're reading
Progress is saved at the sentence level and synced, so a PDF you start on your phone during a commute can pick up on a laptop later at the exact point you stopped. If you want someone else to hear a specific section, you can share a link to the listen starting at a chosen sentence, and it opens in their own library without costing you any of your minutes.
Pricing is per minute rather than a subscription: one minute free with no account, twenty minutes free with an account, then packs of minutes that never expire. For someone who mostly needs to get through the occasional long PDF rather than listen daily, that tends to work out cheaper than committing to a monthly reading app.
Voice choice and speed for dense documents
Not every PDF calls for the same kind of voice. A technical report or research paper might be easier to sit through in a calm, unhurried delivery, while a news roundup or newsletter might suit a brisker, newsreader-style pace. ReadLoud has 30 voices across four engines, Fast as the default, Studio and Gemini 3.1 for higher fidelity, and Narrator, built specifically for audiobook-style narration across more than 50 languages and locales. The Gemini-based voices also take short delivery instructions, calm, teacher, podcast host, storyteller, and a few others, so you can match the voice to the material rather than accepting one default tone for everything you upload.
Speed runs from 0.5x up to 4x with pitch preserved, useful for a dense PDF you want to slow down for versus a familiar report you already skimmed once and just want to confirm by ear at a faster pace. You can preview any voice before committing to it and switch mid-document without losing your place, which matters on a long PDF where the first few pages might call for one voice and a later appendix might read better in another.
When the built-in tools are still the right call
None of this means Select to Speak or Google's own options are wrong to use. For a single page, a form you need to check quickly, or text you will only ever look at once, the built-in accessibility tools are faster precisely because there is no upload step. The conversion route earns its extra minute specifically on PDFs long enough, or important enough, that you would rather listen through them properly than piece them together screen by screen.