Leader length depends on the type of fishing you are doing and the conditions, but a general guideline would be 6-12 feet long. A good place to start is with a 9-foot tapered leader. If you are fishing to spookier fish, add a section of tippet and lengthen that out to 12 feet or so. If you're fishing for bass or other more aggressive species, you can go with a 6 to 7.5-foot tapered leader. Shorter leaders often work well when fishing streamers to help you control the heavier flies as well.