Here's the information straight from the flickr.com site:
Are there limits on file sizes or file types for uploads?
If you have a free account, each photo you upload must be less than 5MB in size. If you have a pro account, each file must be less than 10MB.
Flickr officially supports JPEGs, non-animated GIFs and PNGs. You may also upload TIFFs and some other file types, but they will automatically be converted to and stored in JPEG format.
As you publish photos they are compressed and re-sized by Flickr (if necessary) in the following sizes:
75x75 pixels
100 pixels (on the longest side)
240 pixels
500 pixels
Large (which will be 1024 pixels if it exceeds that length)
And the original size (if you hold a pro account)
You can access all of these sizes for a photo via a link under the photo title labelled 'All Sizes' on its individual page. There's also a link labelled "See different sizes" under the Additional Information heading.
We also store your high-resolution originals for you if you have a Pro Account, which you (and your friends with Pro Accounts) can download again at anytime. All Pro Account holders can access public photos and download the high-resolution (original) size, unless you specify who has access to the downloadable image.
Now, I am not using anything close to a professional level camera, nor am I putting together panoramic shots or 360's. My hiking/packing camera is a tiny Sony DSC-S600, 6MP, point+shoot. But what the hell, it's light and it takes great shots. My pics can be seen at
www.flickr.com/photos/moosepics621. If I ever get around to saving money for a new computer/camera, then I'll probably look at a different site.
-L
...and you get a discount, too! )
