Depending on how a server is set up, your WordPress installation might not allow you to upload files larger than say, 20 MB, or at least that’s how it was for me.
Upload form may give you an error saying “This file is too big. Your php.ini upload_max_filesize is 20M.” (or some other number)…
This is actually not really a problem with WordPress as much as it is a problem with your server’s php installation settings. Fortunately, it’s pretty easy to fix. If you see a file in your root directory called php.ini you can probably take care of this problem by following these intructions
However, if you are using 1and1 web hosting, like one of my recent clients, you wont see a php.ini file hangin around in your root directory. 1and1 doesn’t give you access to this file. Don’t cry. You can change the php.ini file, that you don’t have access to, by uploading a new one containing only the parameters you want to change, to every directory where you want the php rules to be changed, this means the root “/” the website’s folder if there is one “/website/” the sub-folder for wordpress if there is one “/blog/” and the directory called “/wp-admin/”
The file only needs to have these lines in it
upload_max_filesize = 100M
post_max_size = 30M
“M” stands for Megabyte, if that’s not completely obvious. And you can put any value you want here. I went with 100MB for uploads.
I’m leaning toward being cautious here. Probably you can just put one of these files into /wp-admin/ but I’m not sure. Also, you may be able to delete them once you put them in place and refresh the wordpress dashboard. I’m not sure about that either.
I eventually found this info after much googling here on 1and1’s page about this. Also included is how to do this using .htaccess which is what you need to do if have a Managed Server running PHP as an Apache Module.