What the rule organises
Game fish records are not kept as a single list. They are kept by line class, so that a fish taken on light line is compared with other fish taken on light line rather than with everything ever landed.
A class is a category expressed as a strength, published in both metric and imperial. The rule attached to it is the part that reaches a spool on a shelf: the line must test at or under the class it is entered in. A line that tests above its label puts the entry in the next class up, or out of the running.
The current list of classes, and the testing procedure, are published by the association. This site does not reprint either, for the reason it gives everywhere else: an organisation’s values change on the organisation’s schedule.
What it does not promise
It does not tell you how strong a spool is. That is the maker’s declared breaking strain, and it is a separate claim.
It does not apply to a knot, and a line breaks at a knot.
It does not cover braid and nylon identically in every category, and where a distinction exists it is the association’s to state.
And it undertakes nothing at all about a fish landed for its own sake, which is almost every fish this site’s readers will land.
Where it shows up on this site
On the line shelves, as the reason a maker might publish a strain under the round number a buyer expects — one of the few cases in this trade where under-claiming is deliberate.
On the boat rod shelf, where some rods are rated in pounds rather than in grams: « 20-30 lbs » on two rods in this corpus is a line class band and not a casting weight, and confusing the two is how a rod gets bought for the wrong job.
And on the scale shelf, because a weight that has to stand up needs a scale somebody can verify.
How it is read here
A page names the class where a maker names one, says that the figure is a category rather than a strength, and prints the maker’s own declared breaking strain beside it. It does not reproduce the association’s table and does not calculate whether a given spool would qualify.
The questions that keep coming back
Does a line class matter if I am not chasing a record?
Only indirectly, and it is worth knowing why: the class system is the reason some makers under-rate their line deliberately, so that a spool sold as one class tests under it. A spool that tests well above its label is unusable for a record and perfectly good for everything else.
Are the classes in pounds or in kilos?
Both — the association publishes each class in metric and imperial. This site does not reprint the table, for the same reason it does not reprint any organisation’s values: it changes on the association’s schedule and not on ours.
Does the class describe the strength of my line?
It describes a category the line must test at or under. The strength figure you buy on is the maker’s declared breaking strain, which is a different claim and is printed on the spool.
Why does this matter to a scale?
Because a record also needs a weight, and a weight needs a scale that can be checked. The association has rules about that too, and they are its rules rather than ours.
Last reviewed 22 September 2026