This is to get an idea of much data you generally have in Joplin. To find out, you can right click on your profile directory at ~/.config/joplin-desktop and check the total size in there.
0 voters
10G may use joplin as a network disk
I'm curious how this relates to actual number of notes for others - for me I am right at 2GB / 9,472 notes / 10,584 attachments / 1,334 tags
860M 
Just a few pictures or documents, mostly from web clips!
6976 notes and 2168 resources for 944 MB. I don't use the clipper that much so I don't have these many small resources associated with clipper usage.
6.8 GB / 4,091 Notes / 7353 Resources
A fair bit of that is 10 years of stuff (read: junk) that I imported from Evernote. I used to store all my scanned documents in Evernote because the Premium version supported full-text search for images and PDFs. I've since started storing my scanned documents in Google Drive instead since they also support full-text search and I like the document organization better. I expect my size will drop eventually.
Joplin rocks! I love all the updates!
i'm only at about 400mb with a couple of thousand notes. Holding out for a drawing feature before Joplin becomes my primary note taking spot 
A note type on mobile that lets you just draw on the screen would be dope! Maybe make a feature request thread if one doesn't already exist?
It's in the feature request list
request here: Drawing with a pen - #37 by segdy
Using 300 Notes , 2 Notebooks, around 200 attachments and 50 tags.
1.5 GB on disk.
Joplin Desktop 2.0.11 Win
Note history: off
Resource downloads: Always
E2EE: On (Both clients)
Because of this question I looked at my config folder and saw it was 384MB. This was primarily the Resources folder.
I was aware that in the past people have raised questions on this forum about Joplin purging old data (or not) and wondered if the config folder size was actually a measure of how much data Joplin was actually storing.
So, out of curiosity, I created a JEX export of everything and imported it into another copy of Joplin which was synced (E2EE) to an empty sync target. I then checked the size of the new config folder and saw that it was only 110MB.
Therefore this is essentially the same data in both clients, but the "used" client uses 3.5x as much space as the "fresh" client. I suppose that the "used" client may be waiting to flush some unused data but the notes are primarily text and the resources do not change that much
This suggests that about 70% of the data in my local config folder is stored unnecessarily?
It's not a problem when talking about an extra few hundred MB but some here are reporting 10GB+ config folders.
Looks like there's a bug in how Joplin deals with deleted resources (or maybe it's by design) -- even if you disable note history, Joplin would still keep resources around for the time specified in options (Keep note history for (days) in Options - Note History). And if you set it to 0 then it'd still default to 24 days.
notes 3304/32MB (sqlite)
resources 738/141MB
712 notes, 138 MB
899 notes, 987 resources, 114 folders.
In total around 2 GB of data.
Edit: But as @dpoulton wrote, my .jex backup file is only around 650 MB big.
I also noticed when deleting a resource from the note attachments page the file indeed is removed from the .resource folder, but its equivalent .crypted file is not.
I think the total size of all user data isn't the limiting factor in using Joplin.
A few huge pdf files, videos or photos embedded in the notes can easily blow up the database size without having any serious impact on the app.
I'm more worrying about how a large number of notes and/or tags will affect the stability and performance of Joplin. 
“Right-click on ~/.config/joplin-desktop” is something that works neither on my Linux nor my Windows desktop. It’s either du or %APPDATA%\Joplin.