Wholesale Inspector has a 30mb file limitation. There is currently no limit on the number of products that can be run in a single file.
If your file is greater than 30mb, then you will need to reduce the file size in order to get it to run. Don't worry, this is usually very easy!
You will want to
Open the file in your favorite spreadsheet software (usually Excel)
Find the description column and delete that
Resave the file
This will usually bring the file size down dramatically, as the descriptions contain most of the information that causes the file size to be big.