Getting started: Fly sizes

A northern pike caught on a size 2/0 fly. Photo by Chris Hunt.

Among the more confusing—and intimidating—aspects of fly fishing is how the fly-fishing world sizes the hooks upon which our flies are tied. There may be nothing more off-putting to a beginning angler than asking a fly shop sales associate what the trout are biting, only to get an answer like, "Well, in the mornings, they're down deep, and you'll need a size 22 Zebra midge under as size 16 Prince about three feet below your indicator on a 12-foot leader, with about two feet of 3x tippet, with another 18 inches of 5x tippet for the dropper."

Come again?

And you wonder why a lot of folks just give up and go back to the baitcaster. 

Flies (and we'll address line weights, rod weights, tippet, etc. in another post) aren't really that complicated. But, like a lot things that have to do with fly fishing, it sure seems so. Here's the simple key. Higher numbers indicate smaller hooks. I would venture to say that the average dry fly used on most freestone rivers in the world would come in at a size 14 or so. That might seem small, but consider that size 22 Zebra midge our fly guy talks about above. That's really small. 

Most dries, nymphs and wet flies are tied in the size 12-18 range. Bigger dry flies, like hoppers and beetles, usually run in the 8 to 12 range, and streamers, like Woolly Buggers and Clousers generally run in sizes 2 to 8. Bigger, salwater flies or "bass bugs" go even bigger. A 1/0 hook or bigger (2/0, 3/0, 4/0, etc.) is generally used for big water, big fish and heavy lines and rods. 

Hooks_J-Hooks.jpg

Here's a great visual explainer from the folks at The Online Fisherman. 

Here's where it gets tricky. Hooks still get bigger than a size 2 (there is a size 1 hook, but most fly-fishing flies are tied on even-numbered sized hooks). Once you go beyond that size 1 fly, the metrics change, and the larger the number, the bigger the fly. Confused yet?

For example, the next hook size bigger than a size 1 is a size 1/0. Bigger still? Size 2/0, 3/0, 4/0, etc.

These are hooks used for tying flies meant for critters like tarpon, barracuda, pike, musky and even sharks. 

In fly fishing terms, think of a size 2 fly as a large fly—usually a streamer— for big fish like salmon, steelhead and bass. Think of a size 24 fly as something likely meant to imitate very small midges and is used to fish for trout (and no ... I don't tie flies that small, simply because fat fingers and aging eyes just can't make it work—I'll leave these flies to the professionals). 

The basic point for most fly fishers and the flies they'll use for trout is this: the higher the number, the smaller the fly. 

— Chris Hunt

For more "Getting started" posts, follow these links:

• https://www.tu.org/blog-posts/getting-started-know-your-trout
• https://www.tu.org/blog-posts/getting-started-from-gear-to-fly
• https://www.tu.org/blog-posts/getting-started-fly-fishing