Fly Hook Size Chart: The Complete Guide to Hook Sizing

How Hook Sizing Works

Fly hook sizes use a numbering system that can seem counterintuitive at first. For standard hooks, the higher the number, the smaller the hook. A size 20 hook is tiny, while a size 6 is relatively large.

Once you pass size 1, the system switches to "aught" sizes written as 1/0, 2/0, 3/0, etc. Here, larger numbers mean larger hooks. A 4/0 streamer hook is significantly bigger than a 1/0.

Common Hook Sizes by Fly Type

Manufacturer Variations

One challenge with hook sizing is that there's no universal standard. A size 14 from Tiemco may differ slightly from a size 14 from Daiichi or Fulling Mill. The gap (distance from point to shank) and overall length can vary between brands.

This is why many experienced tiers stick with one or two trusted brands, or keep comparison notes to know which hooks are interchangeable for specific patterns.

Shank Length Designations

Beyond basic size, hooks are described by their shank length relative to standard:

• 1XL, 2XL, 3XL - Extra long shanks, each X adds one size worth of length
• 1XS, 2XS - Extra short shanks for compact patterns
• Standard - Regular shank length for the given size

A size 10 2XL hook has the shank length of a standard size 8, but maintains the gap of a size 10.

Wire Gauge

Wire thickness affects how a fly performs:

• Fine wire (1XF, 2XF) - Lighter hooks for dry flies that need to float
• Standard wire - All-purpose, good balance of strength and weight
• Heavy wire (1XH, 2XH) - Stronger hooks for nymphs, added weight helps sink

Comparing Hooks Across Brands

When substituting hooks in a pattern recipe, look beyond size number. Consider the hook style (dry, nymph, streamer), shank length, wire gauge, and bend shape. A hook comparison tool or reference chart helps ensure your substitute will produce a fly that looks and fishes like the original.