We try to give you as much information as possible in the description and will mention if an item runs small or large. There are many times, and with certain brands, you will find a size guide above the item description.
For example, this ladies t-shirt runs large and has an oversized fit. There's also a size guide available:
The size chart will pop up like this:
For a generic size chart for standard T-shirts, Sweatshirts, Shorts and Pants, you can find information here