If you have your podcasts set to stream, instead of download, the file size is listed above each episode in feed right next to the upload date. Just set podcasts to stream in settings.
Some RSS feeds have a glitch causing size/length to not show until you play it, but it’s very rare & usually only happens on certain RSS feeds converted from a website. That bug, in my experience, isn’t on AntennaPod’s end and often resolves on its own.
There’s no way to gauge how much cell/WiFi data a download or stream will use beforehand. Knowing the file size is more than enough, and doesn’t matter if you’re streaming. Just clear app cache regularly if tight on storage space.
EDIT: Check your feed update interval settings. The less often it refreshes feeds for new episodes, the less background data & battery will be used. Set it to largest interval & only update on WiFi.
Just to clarify, the file size does appear in multiple places except in the episode details page, where only date & episode length are displayed.
In my mind, the episode details page is the one place where everything about an episode should be displayed with nothing held back.
(In fact, one thing I wish was also displayed here was a hyperlink to the individual episode media file, rather than hiding it behind the 3-dot → Share menu. Also nice to have would be the chapter details too, if they exist. What else…? )
The episode details page is actually just episode shownotes. Shownotes are controlled by the podcaster, and the formatting generated comes from the RSS feed. Idk if you’re familiar with coding or website debugging at all, but it’s worthwhile to look at the feed itself, where you’ll find podcast info in the header section, then episode information listed chronically, with most recent episode on top. This is where you’ll see the title, date, shownotes, cover art, length, tags, audio file link, etc for each episode.
To do this, copy the RSS link from the podcast’s info/about section, and paste in your browser.
If a podcast has chapters, depending on RSS feed type podcast host deploys or podcaster preference, the time stamps show as green (color might differ in diff AP app versions) hyperlinks in shownotes. However, some pods include chapters to help listeners skip ads, and these are intentionally not listed or linked in shownotes. If a podcast has chapters, a “chapters” button displays next to “shownotes” button on episode, which expands chapter list.
For some reason, shownotes take forever to load for me on AntennaPod & it’s an added click to access what you’re asking for, when it’s already in ep feed. It’s much easier to long-press episode & select “share” or “download” from episode list view. I customized a swipe action to download episodes for this very reason (I stream episodes) where I can just long-press for share menu to upload audio file to Drive.