The two main things to consider when choosing a band saw are the depth of cut and the throat. The saw’s depth of cut is the distance from the table to the upper blade guides. Many band saws are marketed on this feature alone, which tells the prospective buyer how thick of stock can be cut using the band saw. However, some saws that have only a six-inch depth of cut can have an optional riser added to the unit which extends the depth from six inches to twelve. This allows some less expensive saws to be able to cut thicker stock, particularly when resawing.

The throat is the distance from the blade to the vertical frame section of the body of the saw. This distance determines the width of cut that can be completed on the band saw. The throat on a free-standing cabinet band saw typically exceeds the 12 to 14-inch throat of smaller, bench-top models. When you see the term “18-inch Band Saw” advertised, realize that it is the throat measurement to which the manufacturer is referring.

Another consideration is the size of the band saw’s motor . Most home-level models incorporate a 3/4 to 1 horsepower motor, whereas professional models will have larger motors with variable speeds. For woodworkers, the variable speed won’t really matter, as slower than max speeds should be incorporated when cutting metals and some hard plastics.

Source : http://woodworking.about.com/od/woodworkingmachines/p/bandsaws.htm