The size and weight of the fly determines what size tippet works best with that fly. A 3wt rod is for smaller flies and the leader will have a lighter tippet. If you were fishing a size 16 fly a 5X tippet would be used. If you were fishing an 8wt rod with a size 6 fly, a size 2X tippet would be called for. The companies making the leaders size the butt of the leader to match a group of fly lines it might be used on. All you have to worry about is what size tippet you will be using for a particular sized fly.
| Tippet Diameter||Tippet Size||Pound Test||Fly Size|
NOTE: Leader diameters and strengths vary from manufacture to manufacture and with different materials or processes.
Here is a quick way to calculate the best size tippet to use on the water. You take the fly size and divide it by 4 and then add 1. For example, take a size 6 hook, divide 6 by 4 and you get one. Add one to that and you get 2. So for a size 6 hook use a 2X leader. You will note that the chart says 1X or 2X will work. The formula is a guide to get you close to the proper sized tippet on the water. In this case you use the leader that is most appropriate for the size of the fish.