Ok, so it says

Approved: 0
Deleted: 0
Pending: 0
Formula: 10 + (0 / 10) - (0 / 4) - 0 = 10

So according this I should be able to post 10 posts except for some reason when I try to post it still sends me to this formula. How exactly does this formula work, what 0's are for which above?

The amount of images you can upload is equal to ten plus one tenth of the number of your uploads that have been approved, minus a quarter of the number of your uploads that have been deleted, minus the number of uploads you currently have pending.

Understood?
Yes? Good.

So to be fair, the more you upload successfully, the more you can continue to upload. Well what happens when you get so many posts deleted that you can't upload anymore, you just have a dead account?
Apparently I can't upload anything and I just joined, think there's a glitch or bad reception from my end.

Yes, that's the idea. If you post something that gets deleted for whatever reason, it will begin to impact how many images you can have pending at one time, and if you post something that gets approved, which should be everything you upload but everyone has their occasional slips, you can have more pending uploads at once.

Must be a bug or something, PM a mod about it.

SoapBox said:
So to be fair, the more you upload successfully, the more you can continue to upload. Well what happens when you get so many posts deleted that you can't upload anymore, you just have a dead account?
Apparently I can't upload anything and I just joined, think there's a glitch or bad reception from my end.

An example of the latter: forum #32051

Oh, you just joined. That's probably the problem. I believe you have to wait a week after joining before you can upload.

31h253 said:
Oh, you just joined. That's probably the problem. I believe you have to wait a week after joining before you can upload.

Yep, that's your problem right there.

The system prevents new users from immediately posting images for a certain amount of time. The purpose of this is to avoid new or puppet accounts that would be used to post images in rapid succession. This would clog up the amount of new posts updated on the site and make it difficult for the site's staff to fix the situation and remove the abuser.

This limited period also allows new users to get a feel of the site and how it operates. That way, users will know what to upload and how to properly upload images onto the site. This is not always the case, however.

31h253 said:
Oh, you just joined. That's probably the problem. I believe you have to wait a week after joining before you can upload.

Does e621 display this information when a freshly joined user tries to upload something?

Munkelzahn said:
Does e621 display this information when a freshly joined user tries to upload something?

I believe it says you have reached your daily limit, unless it was changed in an update since I last checked.

SoapBox said:
...

Could you try uploading something to e621, take a screenshot of e621's response, upload it to a site like http://imgur.com/ and then post the link here?
Because I'd like to know if e621 displays an informative error message.

Munkelzahn said:
Could you try uploading something to e621, take a screenshot of e621's response, upload it to a site like http://imgur.com/ and then post the link here?
Because I'd like to know if e621 displays an informative error message.

It doesn't, I'll get to work on one now.

Munkelzahn said:
Could you try uploading something to e621, take a screenshot of e621's response, upload it to a site like http://imgur.com/ and then post the link here?
Because I'd like to know if e621 displays an informative error message.

Here is the exact message

Error: Daily limit exceeded
X
News: (Hide)

Hey guys, we don't expect everyone to get along here, but being dicks to each other isn't going to be tolerated. Please try to keep things fun and lighthearted. It would also be a good idea to not bash and insult artists in the comments of images. Believe it or not, they DO see those comments, and they often result in takedown requests.
Upload Limit

You can currently upload 10 posts. This limit is based on the following formula:

Approved: 0
Deleted: 0
Pending: 0
Formula: 10 + (0 / 10) - (0 / 4) - 0 = 10

The limit is clamped between a range of 0 and 20. You cannot upload anything within the first week of registration. You can appeal deletions by posting in the appeal topic in the forum.

It does tell you but only at the very bottom in tiny writing, all a new person really sees is the big red daily limit exceeded at the top, actually I think it would be helpful to know this information before even joining to prevent users from creating accounts in the first place who arent dedicated to the site.