Fly Line Backing Calculator
Loading the right amount of backing keeps your fly line sitting properly on the spool and gives you enough reserve for a big fish's run. Enter your reel and line specs to get a backing recommendation.
About this calculator
Calculate how much backing line you need on your fly reel spool based on reel arbor size, fly line length, and spool capacity.
Frequently Asked Questions
Why do I need backing on a fly reel?
Backing fills the spool so your fly line sits at the correct diameter for casting, and it provides extra line reserve if a fish makes a long run beyond your fly line's length.
How much backing is typical for trout fishing?
Trout setups typically use 50-100 yards of 20 lb backing, while saltwater species like tarpon or bonefish may need 200-300 yards of stronger backing.
Does arbor size affect how much backing I need?
Yes, large arbor reels hold line at a bigger diameter and retrieve line faster, but they generally have less room for backing compared to narrow arbor reels of the same size.