Circular saw blades have different sizes from a few inches to several feet across. Diameter is the span from one edge of the circle to the other measured along a center line. The radius is half that; it is the span from the center to the edge. A saw doesn't have the capacity to cut that deep, though. Maximum depth of cut is less than the radius. It cuts no deeper than 1/3 of its diameter. A 10" saw cuts about 3" deep at maximum capacity, and usually less. A big blade has greater cutting depth. Not only can a larger blade cut deeper, it also has a larger circumference, or the measurement around the rim. A longer cutting length around the circumference makes space for more tips overall. For this reason, bigger blades have longer endurance. Small blades have less circumference circling the rim, which explains how fast they get used up. A big one might last the equivalent of two smaller ones. However, large sizes won't necessarily allow faster feed; coarseness determines that.