If you need to increase the upload limit with Umbraco, this can easily be done if you have root access to your server.

You may have to contact your hosting provider if this is not the case.

First off, you need to update your Web.Config allow the file size you need...

Carry out a search for:

maxRequestLength

Then change the value to the file size you require in kb, for example 100MB in kb is 100000

Once you have made this change you need to update IIS to also increase the limit, there are 2 ways to do this...

First Way:

Navigate to:

cd %winsrv%\system32\inetsrv

and run this code:

appcmd.exe set config "sitename" -section:requestFiltering -requestLimits.maxAllowedContentLength:size in bytes -commitpath:apphost

Second Way:

Open Internet Information Services (IIS) Manager find your website under Sites and click on its name.

Then under IIS click on Request Filtering in this section on the right click on Edit Feature Settings

Then change the Maximum allowed content length (Bytes) in my case again 100MB is 104857600Bytes.

Click Ok and then restart your sites Application Pool

(Original Source)